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New R12 AC system in Dodge D150 blowing relief valve - lack of condenser airflow?

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    New R12 AC system in Dodge D150 blowing relief valve - lack of condenser airflow?

    I just installed an entirely 100% new system in my 89 Ram D150 318. Every single component brand new. I stayed R12 and added exact amount of R12 by weight with my refrigerant scale. Added 44 ounces total.

    It has a brand new fan clutch and condenser and the shroud which fits around condenser and radiator is in place and undamaged.

    Almost immediately upon getting the full charge in, the relief valve built into that “muffler” on the high side discharge line right off the compressor blew and sprayed a bunch of mineral oil and refrigerant out for a few seconds.

    I noticed at idle that the compressor never cycles off although I did not have the idle speed pinned at 1300 as mentioned in the manual - I just left it at base idle. I took the truck for a drive and the vent temps were pretty subpar - we’re talking low 60’s at center vent (and it was about 90 degrees last night in Dallas and about 45% humidity). If I wanted subpar vent temps I’d have gone R134 lol.

    Got it back home and put the gauges on it in the driveway and I see the high side pressure gets up above 400 fairly quickly and after a couple of minutes it blew the relief valve on me a second time. I got out the water hose and with the hose steadily soaking the condenser it nearly instantly brings the high side pressure down and after only a couple of minutes with the hose I get mid 40 degree center vent temps - perfect! However, I do notice that the compressor never cycles at idle - but again I did not adjust the idle speed to 1300 or whatever is called for in the manual and again manual states this is normal around this current ambient temp.

    So my questions are -

    1. How can the OE fan setup be so woefully inadequate?? This is so surprising to me. Is this a common issue with AC systems in these trucks?

    2. What exact conditions should cause the cycling switch to cycle? The manual mentions a range of temperatures (68 to 90 degrees) in which it should cycle and does also mention that above 90 degrees it may not cycle at all which is normal. Given that, and that I was right there around 90 degrees ambient temp... perhaps the fact mine never cycled is normal. It doesn't however list the actual pressures which is what I'd be curious to see.

    3. Is there any reason I shouldn’t just add a couple of slim high power electric fans on the front of the condenser run off a relay activated by the compressor turn on wire?

    4. What should I do about my lost oil? I am well aware that refrigerant oil always “looks” like more than it is when you see it puddled or spray out but I’d guess it might be at least 1/4 oz lost. Is it worth it even trying to bother to add some back? I started out with a bit over 7.25 oz total system volume. I have one of those dye injection syringe deals I could probably add a bit back.

    Thanks for any help/tips. Really looking forward to some good AC in this bad boy finally.

    #2
    Welcome! OK - all new parts then this? I only think I know why. If using the OE listed charge and true new still made new replacement parts if only the condenser is no longer Tube and Fin you would reduce charge by perhaps 10 oz is then correct so that could explain it.

    If so you need to tell me/us just what you found for parts for that guess to apply.

    Been there done that and the box for a new condenser said reduce the capacity by 10oz on a 44oz system just happened to be a car! The blow-out valve was expecting either pressures for R-12 when to blow or for 134a most would have converted long ago now and they do put out as cool as R-12 just not at the higher volume without total HE 134a specified parts or compatible with it. Switches if this is a CCOT set up (perfect score never seen a Mopar truck with A/C that I recall!) would be set for 134a should be adjustable just the one with R-12 for '89 on or near the accumulator.

    It shouldn't be ruined still a guess things usually are not there in person. The blow-out valve may or may not seal when it self reset beware of that.

    If you still have it intact now is the time to check for leaks at that blow-out valve.

    More: I can't find and quit looking or exact OE R-12 parts always reduced amount of charge. Next try lower charge to 60% of what you thought was OE and work up but may be best at 80% would stop there and test it out, drive it, turns, stops and starts and check again. Tweak these the factory specs are almost certainly off now and lower even with R-12 would explain what happened if all else was right,
    Tom
    MetroWest, Boston

    Comment


      #3
      I've never seen a pressure relief on a muffler... That aside, I would go with an electric fan or two. I see pressure problems like you describe (less the discharge valve release) all the time here in our shop. The clutch fans don't seem to move enough air until the bi-metal on the fan gets hot, which means high pressures until the fan decides to get its act together. I never really like that.

      *If* that system uses an expansion valve, then that's not really a cycling swicth. it's a low pressure cut-out for system protection.

      I just think It's awesome that you put an R12 system together!

      Comment


        #4
        Totally spot on CJB. I went thru 3 new bimetal fan clutches on a car I still have NONE pull strong when hot nor spin/coast when cold as they are meant to? IDK why new they did.

        I will not just because but the non thermo clutches pull obnoxiously too hard all the time or ones customers requested to save a buck all did. Took those off for Winters if orig was just weak put that one back on avoid that roar all the time.

        Dodge Trucks? No telling where they put a blowout valve? I didn't design it
        Tom
        MetroWest, Boston

        Comment


          #5
          Ok, 1st and foremost STOP. You've got a serious problem and it might be a poorly made component and nothing you did wrong, but before you can diagnose further I have a few suggestions and comments.
          1 I believe Dodge at this time was not using a CCOT system, they were the last American made product to shift to the CCOT. A Tx valve system will only cycle under 1 or 2 conditions. 1 the evaporator is cold enough to trip the frost switch, and 2 if it has a high pressure cut out and the high pressure exceeds that setting. We know yours doesn't (yet) have a HPCO because you are blowing the relief. SO don't expect the compressor to click on and off, it ain't going to happen.
          You've got a serious problem, and I think it is a blockage somewhere, not just a under-preforming condenser. I have had a degraded condenser trip a HPCO but it took some time of heat building in the system to reach 400 psi.
          1st thing I would do to diagnose is find what the system uses for a low pressure cut-out. Likely a switch on the receiver. I would replace this switch with a "binary" switch. This will shut the compressor off if the system is too low AND if pressure is too high. This will save precious R 12 and prevent further blow offs while you search for the problem. With a binary switch in place you can concentrate on looking for the problem with worrying the system is going to blow while you are looking at something other than gauges.

          Something is screwy in Denmark. with the binary in place and the system charged, it would run it and feel the condenser, it should start out hot and stay relatively evenly warm across and down to the bottom, and the outlet should be noticeably cooler then the inlet. Check the sides and if one is hot all the way down and the other cooler, than likely a defectively made condenser.
          A severe plug or defective hose anywhere in the system would also see high pressure before and lower than normal pressure after the restriction.
          You didn't post any pressure readings but that would help.
          My experiences with Dodge products A/C is from the era of RV-2 compressors and EPR in the suction line. I think this is after that era so pictures would help.
          Edit:
          All refrigerant can both burn and blind you on a hose burst, and is esp dangerous when searching for problems like you have. The HPCO is one safe thing, but wear goggles and gloves with long sleeve shirt and pants. You know you have a serious problem, and now is the time to fully protect your self.
          Last edited by Cornbinder89; 07-06-2018, 01:21 PM.

          Comment


            #6
            Originally posted by Tom Greenleaf View Post
            Welcome! OK - all new parts then this? I only think I know why. If using the OE listed charge and true new still made new replacement parts if only the condenser is no longer Tube and Fin you would reduce charge by perhaps 10 oz is then correct so that could explain it.

            If so you need to tell me/us just what you found for parts for that guess to apply.

            Been there done that and the box for a new condenser said reduce the capacity by 10oz on a 44oz system just happened to be a car! The blow-out valve was expecting either pressures for R-12 when to blow or for 134a most would have converted long ago now and they do put out as cool as R-12 just not at the higher volume without total HE 134a specified parts or compatible with it. Switches if this is a CCOT set up (perfect score never seen a Mopar truck with A/C that I recall!) would be set for 134a should be adjustable just the one with R-12 for '89 on or near the accumulator.

            It shouldn't be ruined still a guess things usually are not there in person. The blow-out valve may or may not seal when it self reset beware of that.

            If you still have it intact now is the time to check for leaks at that blow-out valve.

            More: I can't find and quit looking or exact OE R-12 parts always reduced amount of charge. Next try lower charge to 60% of what you thought was OE and work up but may be best at 80% would stop there and test it out, drive it, turns, stops and starts and check again. Tweak these the factory specs are almost certainly off now and lower even with R-12 would explain what happened if all else was right,
            Thanks, I've actually been a long time member on the other forum. Went to post today and saw that it's moved... so I'm new, but not new lol. Yes everything is entirely 100% new, even the hoses - I always prefer to just go brand new on everything when I re-do AC systems.

            The condenser is a tube and fin style, and is the exact same size/shape by all accounts than the OEM one I removed, as is the evaporator. If the total system capacity of this new setup is any different than OEM - it's got to be darn near negligible.


            Originally posted by CJB View Post
            I've never seen a pressure relief on a muffler... That aside, I would go with an electric fan or two. I see pressure problems like you describe (less the discharge valve release) all the time here in our shop. The clutch fans don't seem to move enough air until the bi-metal on the fan gets hot, which means high pressures until the fan decides to get its act together. I never really like that.

            *If* that system uses an expansion valve, then that's not really a cycling swicth. it's a low pressure cut-out for system protection.

            I just think It's awesome that you put an R12 system together!
            I haven't either, and thought it was weird. The service manual indicates that the factory pressure relief was located on the drier itself - but I checked the OEM drier I removed and there's definitely not one there - just an empty threaded hole that does not pass through. My OEM hose does also have this pressure relief on the muffler itself same as my new aftermarket hose. Here's a great shot of the hose from Rock Auto (same hose I bought - Four Seasons brand):



            Although, maybe I'm wrong and it's NOT a pressure relief valve? No clue what else it would be and it's definitely venting up between 400-450 PSI lol.

            The system does have an expansion valve but it is the block style. The service manual is calling it an “expansion H valve” and the switch in question is also being directly referred to as a “damped pressure cycling switch” in the service manual as well.

            And thanks, I very much prefer staying R12 on factory R12 vehicles like this. The whole thing that got me into AC “work” in the first place was several failed R134 conversions on my and my buddy’s little Civics back in the day which led me here (well, the old forum). I ultimately ended up converting my Civic back to R12 and still have over 40 lbs of R12 plus at least a dozen cans of the stuff.. so I really have no desire or incentive whatsoever to bother to convert anything to R134 that wasn’t factory. I’m in Texas – gotta have good vent temps.

            Originally posted by Cornbinder89 View Post
            Ok, 1st and foremost STOP. You've got a serious problem and it might be a poorly made component and nothing you did wrong, but before you can diagnose further I have a few suggestions and comments.
            1 I believe Dodge at this time was not using a CCOT system, they were the last American made product to shift to the CCOT. A Tx valve system will only cycle under 1 or 2 conditions. 1 the evaporator is cold enough to trip the frost switch, and 2 if it has a high pressure cut out and the high pressure exceeds that setting. We know yours doesn't (yet) have a HPCO because you are blowing the relief. SO don't expect the compressor to click on and off, it ain't going to happen.
            You've got a serious problem, and I think it is a blockage somewhere, not just a under-preforming condenser. I have had a degraded condenser trip a HPCO but it took some time of heat building in the system to reach 400 psi.
            1st thing I would do to diagnose is find what the system uses for a low pressure cut-out. Likely a switch on the receiver. I would replace this switch with a "binary" switch. This will shut the compressor off if the system is too low AND if pressure is too high. This will save precious R 12 and prevent further blow offs while you search for the problem. With a binary switch in place you can concentrate on looking for the problem with worrying the system is going to blow while you are looking at something other than gauges.

            Something is screwy in Denmark. with the binary in place and the system charged, it would run it and feel the condenser, it should start out hot and stay relatively evenly warm across and down to the bottom, and the outlet should be noticeably cooler then the inlet. Check the sides and if one is hot all the way down and the other cooler, than likely a defectively made condenser.
            A severe plug or defective hose anywhere in the system would also see high pressure before and lower than normal pressure after the restriction.
            You didn't post any pressure readings but that would help.
            My experiences with Dodge products A/C is from the era of RV-2 compressors and EPR in the suction line. I think this is after that era so pictures would help.
            Edit:
            All refrigerant can both burn and blind you on a hose burst, and is esp dangerous when searching for problems like you have. The HPCO is one safe thing, but wear goggles and gloves with long sleeve shirt and pants. You know you have a serious problem, and now is the time to fully protect your self.
            Well - the service manual DOES directly state that in the current conditions last night that the system not cycling is perfectly normal. So, not to discount what you're saying - and in fact your response is the exact sort of wait-a-minute-there-might-be-more-here-than-condenser-fans answer I'm looking for - but the fact that it didn't cycle last night isn't thus far an issue per se as it's normal behavior for the conditions (idle, and 90ish F ambient temp).

            Also, with the water hose on the condenser the pressure never gets high enough to trip the relief valve and the system behaves as one would expect - great vent temps, perfectly fine pressures.

            So, the system uses the "damped pressure cycling switch" as I mentioned above. I can't however find what exact pressures it's looking for and the service manual doesn't state specifically. This switch is on the low side, and as best I could tell on the gauges, the low side never fluctuated that much - between 35-45 or so, and so I can't imagine that it would have stepped in anyway. Only the high side is getting super high pressure.

            The system also "feels" like it's working right. The suction hose frosts/condensates. The discharge side line is very hot between the compressor and condenser - almost too hot to the touch, but then coming out of the condenser it's much cooler between condenser and the expansion valve.

            Comment


              #7
              Never came across a low side cycle switch on a Tx valve system, but I don't claim to have seen everything, Not sure how it would work either, I'm still trying to wrap my head around what good it would do, the only low pressure switches on Tx valve that I have come across latch a relay to lock off the system when it is low, and they work much sooner then conventional high pressure switches and require liquid refrigerant to be loaded into the system when charging and empty system before finish charging vapor or they will lock down the system and need to be re set for it to take in more vapor.
              Still think a binary in the high side is worth installing and can be left in place after it is solved, and will continue to protect the system.
              Block type Tx valves are sometimes refered to as H valves because of the 4 lines that go into the block, whereas a conventional Tx only goes into high pressure line but may have an equalize line to the outlet of the evaporator.
              I would be interested in what you find out on the low pressure switch, I just can't see the reason unless they are trying to use it like the old EPR? but why not just use a frost switch in the evaporator? a frost switch would be more accurate at controlling evaporator temp.

              Comment


                #8
                Originally posted by james89dx View Post


                The system also "feels" like it's working right. The suction hose frosts/condensates. The discharge side line is very hot between the compressor and condenser - almost too hot to the touch, but then coming out of the condenser it's much cooler between condenser and the expansion valve.
                This statement make me think you should be looking long and hard at the condenser for a spot where it goes from hot to cool, indicating a restriction. When systems I worked on had a degraded condenser that wasn't plugged or didn't have a restriction, just not shedding heat, the outlet was very warm to hot to the touch, and even then, the pressure was below 400 unless run for a long time.
                With a restriction, the condenser becomes "smaller" in that the only useful area is that before the restriction, the area after the restriction acts like a big receiver and the outlet will be cool (not as cool as ambient but nowhere near the 200 deg you are seeing at the inlet.

                Comment


                  #9
                  Originally posted by Cornbinder89 View Post

                  Never came across a low side cycle switch on a Tx valve system, but I don't claim to have seen everything, Not sure how it would work either, I'm still trying to wrap my head around what good it would do, the only low pressure switches on Tx valve that I have come across latch a relay to lock off the system when it is low, and they work much sooner then conventional high pressure switches and require liquid refrigerant to be loaded into the system when charging and empty system before finish charging vapor or they will lock down the system and need to be re set for it to take in more vapor.
                  Still think a binary in the high side is worth installing and can be left in place after it is solved, and will continue to protect the system.
                  Block type Tx valves are sometimes refered to as H valves because of the 4 lines that go into the block, whereas a conventional Tx only goes into high pressure line but may have an equalize line to the outlet of the evaporator.
                  I would be interested in what you find out on the low pressure switch, I just can't see the reason unless they are trying to use it like the old EPR? but why not just use a frost switch in the evaporator? a frost switch would be more accurate at controlling evaporator temp.
                  I ended up looking up the new switch I bought, and found that Rock Auto has quite a bit of info on it. Looks like the cut off/on range is 22 and 49 PSI:

                  https://www.rockauto.com/en/moreinfo...084744&jsn=501

                  How exactly would I install and wire a binary on the high side?


                  Originally posted by Cornbinder89 View Post

                  This statement make me think you should be looking long and hard at the condenser for a spot where it goes from hot to cool, indicating a restriction. When systems I worked on had a degraded condenser that wasn't plugged or didn't have a restriction, just not shedding heat, the outlet was very warm to hot to the touch, and even then, the pressure was below 400 unless run for a long time.
                  With a restriction, the condenser becomes "smaller" in that the only useful area is that before the restriction, the area after the restriction acts like a big receiver and the outlet will be cool (not as cool as ambient but nowhere near the 200 deg you are seeing at the inlet.
                  Help me understand this a bit better - are you saying that a properly functioning condenser should NOT be cool to the touch at the outlet and the fact that mine IS much cooler at the outlet is indicative of a restriction?

                  How exactly would I test for a restriction? I have a laser thermometer thing - just kind of check around various spots?

                  Comment


                    #10
                    Well, I posted a response but it says it was flagged for potential spam (??). I had a link to a Rock Auto part in there, maybe that's why.

                    Comment


                      #11
                      It must have been the link, but I approved it.
                      If the condenser is working properly, yes the outlet will be cooler, how cool depends on how much heat is shed, but the important thing is the high side pressure will be much lower than what you are seeing, The pressure should correlate to a condensing temp somewhere between 20 and 40 degs hotter than then air passing thru the fins. You are seeing condensing pressure (temp) of around 200 deg! So the question is why. If there was a restriction in the condenser, flow thru the condenser slows down and gas backs up before the restriction, since the surface area before the restriction isn't enough to get the heat out of the gas fast enough the pressure and temp rise until the refrigerant will liquefy at the temp it is at. Once the liquid makes it past the restriction it will continue to cool and come out the outlet closer to ambient temp.
                      In a condenser that is working properly or if you cool it with water, which can absorb a lot of heat in a small area, the refrigerant will condense at a temp (and therefore pressure) much lower than you are seeing.
                      As to a binary switch, you just need a port on the high side somewhere, you could even use the relief valve port if it is 3/8x24 o ring, and you wire the feed to the compressor clutch to it and then on to the clutch, there are two terminals on the switch and should be marked "1" and "2" power in on "2" and out on "1"

                      According to my book they open at 270-330 psi

                      If you don't have a port you can put a 1/4" flare port in a section of line and they make a switch with a valve depressor that will screw onto a flare port and do it that way as well, switches are made in both 3/8" O ring and 1/4" flare
                      Last edited by Cornbinder89; 07-06-2018, 04:56 PM.

                      Comment


                        #12
                        Another thing that comes to mind, is you may have a fair bit of "non condensable gas (air)" trapped in the system, I trust you pulled a good vacuum before re charging, but is it possible air leaked in during the changeover from vacuum to gas?

                        Comment


                          #13
                          James - you called this all new and original. Nobody used 134a TMK for model year 1989 just maybe a SAAB something came thru about 1991, 1993 could be either speaking model years not when it was actually made. If original VIN# all match up and date just month and year it was assembled.

                          Said that I never saw the pickups with A/C. Just chance they existed no question. Do you have info all the way back on this truck? There was no OE law saying you needed an high pressure cut out just let it blow out in a failure not quit working by pressure too high till it was law for a retrofit to add one.

                          Lost with looking up parts that would be OE already made for both NONE listed were CCOT set ups all used a block for an expansion valve as I would have suspected.

                          Looks like this...….
                          Image of Compressor Works A/C Expansion Valve : Part number 758849
                          I plain can't know what you have called OE stuff. It's listed that way parts sold expecting to be compatible with either R-12 or 134a no surprise there compressor shows it's full of PAG oil if you got one all were rebuilt not new. Info is sketchy just said all were model C171 compressors.

                          This one shows what look like where blow out valve would be? Below,

                          Brass tone thing on compressor.

                          In short there's just lousy info that I found. Understand calling engine a 318 I don't think they ever called it by cubic inches rather a 5.2 liter same thing.

                          In short there's so much room for parts failures now not new old stock but what they could clone I think not trusting capacity.

                          One more. Not for here this is cold country trucks were not for much comfort by Dodge that I knew of till later. A lot of real close aftermarket set ups may have been put on this new before sold as close as they could do.

                          Capacity I don't trust. Just how did you charge it? The problem was instant it may have just choked on liquid so even more IDK what I'd do just for charging with so much lousy into when I just looked.

                          Not real sure just what you have here will leave this thread alone as I just can't know but watching for a fix,
                          Tom
                          MetroWest, Boston

                          Comment


                            #14
                            So, last night I got home from work and installed two 12" Hayden electric fans. I used a standard auto relay and triggered it with the compressor power wire.

                            The two fans fit perfect on the front of the condenser thankfully. All said and done, the fans did help the pressure noticeably and no longer kept blowing the relief valve BUT the high side pressure is still far too high it seems. Dodge doesn't list any pressure ranges at all in the service manual but surely it's not normal to sit idle indefinitely at 350-375 PSI on the high side.

                            I tested the static pressure when I first got home and ambient temp was 85 degrees and 66% humidity. Low side static pressure was right at about 85 but high side was right at 100 - isn't this a high static reading for the high side??

                            I’ll post some pictures of the truck as well as the overall system (more pics to follow in following post due to 4 image count limit) which may help you guys visualize better. Some of these pictures I took after the AC was already running and so you can see the sweat on the lines etc. The picture of the gauges at ~30 PSI on the low side and ~350 PSI on the high side is pretty much exactly how the system sat with very minimal variation for 30 straight minutes of me letting it run. The vent temps were good - 47 at center vent - but again that high side pressure just can't be right!?










                            Originally posted by Cornbinder89 View Post
                            It must have been the link, but I approved it.
                            If the condenser is working properly, yes the outlet will be cooler, how cool depends on how much heat is shed, but the important thing is the high side pressure will be much lower than what you are seeing, The pressure should correlate to a condensing temp somewhere between 20 and 40 degs hotter than then air passing thru the fins. You are seeing condensing pressure (temp) of around 200 deg! So the question is why. If there was a restriction in the condenser, flow thru the condenser slows down and gas backs up before the restriction, since the surface area before the restriction isn't enough to get the heat out of the gas fast enough the pressure and temp rise until the refrigerant will liquefy at the temp it is at. Once the liquid makes it past the restriction it will continue to cool and come out the outlet closer to ambient temp.
                            In a condenser that is working properly or if you cool it with water, which can absorb a lot of heat in a small area, the refrigerant will condense at a temp (and therefore pressure) much lower than you are seeing.
                            As to a binary switch, you just need a port on the high side somewhere, you could even use the relief valve port if it is 3/8x24 o ring, and you wire the feed to the compressor clutch to it and then on to the clutch, there are two terminals on the switch and should be marked "1" and "2" power in on "2" and out on "1"

                            According to my book they open at 270-330 psi

                            If you don't have a port you can put a 1/4" flare port in a section of line and they make a switch with a valve depressor that will screw onto a flare port and do it that way as well, switches are made in both 3/8" O ring and 1/4" flare
                            Before I added the fans last night I tested around with the point and click thermometer around the condenser and couldn't find any discernible or obvious hot or cold spots that would seem like an obvious restriction. So then I just added the fans to move onto my little experiment. I would completely consider a switch on the high side but given the results of my experiment it appears the compressor would forever be shut off by this switch if the 270-330 psi is correct which I explained a bit above.

                            And to answer your other question, yes I vacuumed for well over an hour at 28". I actually ran out of time that night to go ahead and charge it so it sat overnight on vacuum and held the 28" vacuum for a full 24 hours until I could charge it the next night after work. I’m self-taught with AC work but this is probably at least my 20th time vacuuming/charging an AC system and while I suppose anything is possible, I can’t imagine I goofed and introduced air. I’m meticulous about purging the yellow hose, double/triple checking everything is closed off or open or whatever I need to be doing.

                            Originally posted by Tom Greenleaf View Post
                            James - you called this all new and original. Nobody used 134a TMK for model year 1989 just maybe a SAAB something came thru about 1991, 1993 could be either speaking model years not when it was actually made. If original VIN# all match up and date just month and year it was assembled.

                            Said that I never saw the pickups with A/C. Just chance they existed no question. Do you have info all the way back on this truck? There was no OE law saying you needed an high pressure cut out just let it blow out in a failure not quit working by pressure too high till it was law for a retrofit to add one.

                            Lost with looking up parts that would be OE already made for both NONE listed were CCOT set ups all used a block for an expansion valve as I would have suspected.

                            Looks like this...….

                            I plain can't know what you have called OE stuff. It's listed that way parts sold expecting to be compatible with either R-12 or 134a no surprise there compressor shows it's full of PAG oil if you got one all were rebuilt not new. Info is sketchy just said all were model C171 compressors.

                            This one shows what look like where blow out valve would be? Below,

                            Brass tone thing on compressor.

                            In short there's just lousy info that I found. Understand calling engine a 318 I don't think they ever called it by cubic inches rather a 5.2 liter same thing.

                            In short there's so much room for parts failures now not new old stock but what they could clone I think not trusting capacity.

                            One more. Not for here this is cold country trucks were not for much comfort by Dodge that I knew of till later. A lot of real close aftermarket set ups may have been put on this new before sold as close as they could do.

                            Capacity I don't trust. Just how did you charge it? The problem was instant it may have just choked on liquid so even more IDK what I'd do just for charging with so much lousy into when I just looked.

                            Not real sure just what you have here will leave this thread alone as I just can't know but watching for a fix,
                            Yes it is all new aftermarket from Rock Auto. I'm not sure what the TMK acronym is that you mention?

                            My expansion valve looks exactly like the one in your picture. The new (aftermarket) compressor did come with oil installed in it (surely PAG), but I drained it all out as I do with all compressors so I can start with an exact known oil amount.

                            My new compressor does NOT have a valve on the top like in your picture. All it has is one single service port on the back directly facing the TBI and is actually somewhat difficult to access. The OEM one had the service port in that exact spot of the valve in your picture though and so I suspect the one in your picture is a service port as well.

                            The 44 oz capacity I got straight from the manual and there is also an OE label on the top of the fan shroud that also lists 44 oz so I am confident that amount is correct. I charged it with my refrigerant scale and am confident I hit the 44 oz almost right on the head (well, prior to the relief valve going off on me twice).

                            My truck was a one-owner vehicle. It was the proverbial old man who only drove it to church and the store kind of thing but it sat outside and got all faded only on one side lol. Thank goodness he kept the cab parked in the shade because the interior is immaculate. Only has 100k miles. He died and the nephew inherited it, thought it was "junk" and sold it to me. It ran but very very badly and had numerous leaking freeze plugs so it would overheat. I spent last summer overhauling the engine (no internal work - just pulled it to do all freeze plugs, all new gaskets, rebuilt the TBI, timing chain, new water pump, new oil pump, all new ignition system, hoses, new brakes, etc). It runs and drives like an absolute dream now even though the engine "looks" junky. Anyway, no, I don't have documentation for work done or even the purchase order or anything, but I have no doubt the AC system was factory installed. Keep in mind this is an 89 D150 - and Dodge made the first gen D150 for a looooong time, so this looks old but is actually fairly modern and I can't imagine in the late 80's and early 90's that factory AC wasn't the norm on these. I'm not even a Dodge fan at all but I love this truck and jumped on it for the price, interior condition, and rareness. I really wanted a GM but pounced on this when I spotted it on CL. Mainly needed a "beater" truck for hauling projects/junkyard runs/Home Depot runs/etc. so I longer had to borrow my buddy's truck and I'm trying to finish it off with AC. Ironically now his truck is broken down and he has to borrow mine often lol. Few more pics of the truck to follow.

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                              #15








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                                #16


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                                  #17
                                  Interestingly, I found this thread with a guy having basically the exact problem as me on a Dodge forum:

                                  https://ramchargercentral.com/diesel...ide-pressures/

                                  His is a diesel truck but the system should basically be the same.

                                  He ends up following up with his thread saying that his issue was a low charge level? That can't be right, can it? Why/how would a low charge cause such high pressure on the high side?

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                                    #18
                                    Pressure in an A/C system tells you one thing and one thing only, the temperature of the refrigerant at the point on phase change (gas to liquid or liquid to gas). From that reading it is up to the mechanic to determine what the root cause is.
                                    Your high side pressure is saying the refrigerant is too hot and is not shedding heat at the condenser. wetting the condenser get the heat out and the pressure down. In other words your condensing temp is too high. I have to admit I am puzzled as to why that would be. It looks like your OEM baffles and seals are in place to pull air over the condenser.
                                    See if the fan will hold a normal sheet of paper against the condenser to test flow, and also try the same test with a note card (heavier).
                                    On my heavy trucks I had similar problems, which I solved by putting an aftermarket 3 ton condenser in it. Air flow wasn't the problem but fin count, tube size and spacing were. This was on a semi converted to 134a from R 12. It now cools better on 134a then it ever did on R12 with the factory condenser. I had tried a factory condenser but was still having high head pressure, now it at 90 deg it is rock solid 165 psi high side!
                                    The newer parallel flow condensers have a lot more BTU capacity for a given size than the old tube and fin, their drawbacks are the tubes are small and can't be flushed if a debris is in the system as some feel they aren't as sturdy as tube in fin in terms of impact resistance.
                                    By the size of the opening I don't think you'd have any trouble fitting a 3 ton unit in there, but you'd have to make custom hoses for it.
                                    It has been my experience that OEM fit the absolute minimum condenser that engineering says it needs, and the result is marginal cooling from the get go.

                                    I read what he said and admitted useing a "fish scale" to measure the refrigerant and I think he just plain got it wrong. No way can I see low refrigerant causing that high a highs side pressure.

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                                      #19
                                      A reason maybe: What or who made those fans? They don't channel air thru even whole condenser and round shroud inside by the time engine coolant is flowing would bet radiator's heat is blowing backwards right thru condenser! As Cornbinde89 already suggested put paper on it while fans on bet it blows air right back out.

                                      Lists a fan clutch (who knows?) not this by rights should be designed for this truck specifically doubt fans were? Nice pics do help, could use more targeting fan(s) and if belt driven fan still on that too.

                                      Or just the paper test, smoke test (machines for that) but can get away with a cigar/cigarette or incense stick you'll find airflow is all wrong.

                                      It's possible for two fans in series if so fight each other and result in unseen "cavitation" like a motor boat's propeller if you've experienced that just flails sucking air not water in that case. In vehicles, any with this layout air can only exit around and down and out as much as possible all around doesn't really want to, you force it to flow over total condenser and radiator or end up they just fight and blow backwards until if ever vehicle speed overcomes it. To force that even more with a billboard front (trucks more than most cars) use an air dam to create a vacuum which forces air to head down and out, If pressure from speed would defeat itself. Follow me?
                                      Tom
                                      MetroWest, Boston

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                                        #20
                                        So just to update this thread. That night I added the fans I let the truck sit and idle for 30 mins in the driveway as I tested the pressure etc. High side still seemed far too high for me but center vent temp was down into the 40’s which was great.

                                        Saturday in the heat of the day I went to take it for a solid 30 minute test drive. Center vent temps were awful – stuck between 60-65 the whole time and the relief valve blew a couple of times for sure. What a mess. This is officially driving me crazy.

                                        I ordered a new condenser and expansion valve that I’ll swap in. Can’t imagine what else the problem could be other than perhaps a manufacturing defect that caused a blockage in the condenser or something. I know it’s not debris because I’m meticulously clean when putting AC systems together.

                                        Sure hate losing almost 3 lbs of R12 though. I don’t have a recovery machine so no way to recover what’s in there now.


                                        Originally posted by Cornbinder89 View Post
                                        I read what he said and admitted useing a "fish scale" to measure the refrigerant and I think he just plain got it wrong. No way can I see low refrigerant causing that high a highs side pressure.
                                        I agree with this that low refrigerant shouldn't (couldn't?) cause super high high side pressure. Given that, I doubt he's "lying" that his system was fixed after a fresh re-charge - but probably misunderstanding the reason - so what would explain his fix now? He had some sort of restriction that somehow got cleared by him (presumably) doing an evac and re-charge?

                                        Originally posted by Tom Greenleaf View Post
                                        A reason maybe: What or who made those fans? They don't channel air thru even whole condenser and round shroud inside by the time engine coolant is flowing would bet radiator's heat is blowing backwards right thru condenser! As Cornbinde89 already suggested put paper on it while fans on bet it blows air right back out.

                                        Lists a fan clutch (who knows?) not this by rights should be designed for this truck specifically doubt fans were? Nice pics do help, could use more targeting fan(s) and if belt driven fan still on that too.

                                        Or just the paper test, smoke test (machines for that) but can get away with a cigar/cigarette or incense stick you'll find airflow is all wrong.

                                        It's possible for two fans in series if so fight each other and result in unseen "cavitation" like a motor boat's propeller if you've experienced that just flails sucking air not water in that case. In vehicles, any with this layout air can only exit around and down and out as much as possible all around doesn't really want to, you force it to flow over total condenser and radiator or end up they just fight and blow backwards until if ever vehicle speed overcomes it. To force that even more with a billboard front (trucks more than most cars) use an air dam to create a vacuum which forces air to head down and out, If pressure from speed would defeat itself. Follow me?
                                        Hayden made the fans – they are universal slim electric fans. Your question(s) here about whether or not adding pusher fans to the front of a factory setup that is designed with puller(s) behind the radiator is one I’d struggled with years ago when doing my Civic AC system. I was concerned they would “fight” each other as you suggested. The factory systems on the EF Civic and CRX just do not perform well at idle no matter what you do, and so my fix was adding Haydens to the front of the condenser. I really thought long and hard about it before doing it and trying to wrap my head around the “science” of it but all said and done I did it anyway on the Civic. Voila, worked like an absolute dream and really helped my idle performance with zero negative impact whatsoever. This has been 6-7 years ago now and still going strong, almost daily driven.

                                        I have no doubt the fans on the front of the truck are only adding to condenser performance. In fact, the longer I test drove the truck, it actually seemed to slowly suck engine temps further and further down and the longer I drove even in 90+ Texas heat the factory temp gauge was slowly falling below the middle mark it seems to sit on. So, if anything, the newly added supplemental condenser fans are actually working TOO well and yet the high side pressures are still far too high on the system.
                                        Last edited by james89dx; 07-09-2018, 11:41 AM.

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