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Mystery to me

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  • Mystery to me

    First of all, let me apologize for this long narrative on my first post as a member, but if you are interested enough to read it, it will save on the back and forth questions; thanks in advance for any opinions and help; obviously I don’t know what I am doing so I won’t pretend to try to help others but I could use some; I’m a 63 year old guy, still working, and I guess my hobby is keeping the family fleet running; I have an old 2000 Honda Odyssey with 225,000 miles but it runs like a top and is the best vehicle I have ever owned; I do all the light weight maintenance even shocks, struts, cat, intake manifold removal to clean EGR passages, etc., except one transmission replacement at 130,000 miles and CV joints and such; 2 years ago the OE compressor locked up on a busy interstate, melted the serpentine belt off, got towed in, but clutch pulley spun freely when AC was off, so we installed my spare belt, disabled the AC button, and drove home; May ’19 bought new Denso 471-1276 compressor (containing enough oil for entire system), Denso condenser, UAC high P liquid line hose, UAC high P vapor line hose; finally got up enough nerve to start and installed it all 2 weeks ago; didn’t want to take evaporator (front) and evaporator (rear) out to flush, or flush all remaining piping; told him my plan and the Denso tech told me to drain 4.5 oz oil out of new compressor, put 3 oz in new condenser, and dispose of 1.5 oz; I did; so, I rolled the dice on not flushing and hoped the old compressor didn’t die the “black death” and if there was any metal shrapnel, hopefully it stayed in the old condenser; After taking off parts, just to see, I flushed the liquid and vapor hoses with AC flush into a clear glass; no particles whatsoever, but with magnifying glass I saw two nearly microscopic black dots (maybe rubber?) and saw no glint of metal; certainly nothing that the “thimble style” filter I bought but didn’t use would ever catch; encouraging; inside the openings of compressor I saw black residue on surfaces that a few specks kind of stuck to the magnet but were so small (tiny specks under ever 25X magnifier) that it could have been electrostatic attraction and didn’t glint like metal (more encouragement); pulled my USA-made Uniweld manifold gauges and USA-made Mastercool 2 cfm vacuum pump out of storage for >20 years (successfully converted an ’85 Crown Vic from R12 to R134A last time); removed the fresh oil it was stored with, added fresh oil to pump, turned on and heard snap; motor runs, pump doesn’t; rented a brand new cheapo Chinese vacuum pump from O’Reily’s; works so well I just kept it; pulled vacuum about 2 hours, fully charged with 30 to 31.5 oz R134A (system calls for 30-32 oz). Compressor ran fine, air got cool but not cold, but I could not get it any better than 75 psi low side and 112 psi high side (84 degrees ambient air temp, 70% humidity); left it alone; internet researched a cause; maybe the thermal expansion valve is stuck open after long layup with no movement; left alone so not to harm compressor with liquid freon; ordered UAC evaporator and Denso expansion valve; installed them after cleaning evaporator housing with Clorox cleaner and toothbrush till clean as a whistle-smells so clean now; added 1 1/3 oz (40ml) oil to new evaporator; pulled a 3 hour vacuum; Using low side port, tried to add 8 oz from first can using electronic scale but could only get 5 oz vapor phase in; turned on AC to get help of compressor but it drew out the rest of the 12 oz can before I noticed; while I was inside van cabin, I had it stable but the can somehow turned sideways; don’t know if that slugged the compressor or not; guessed I’d try partial withdrawal of 8 oz on can #3; air getting cool; connected second can, it drew out about an ounce so slowly; to hasten withdrawal from can I thought (probably stupidly) I would turn on rear AC fan; cool air now coming from front and rear vents too; then a minute later, air starts to warm; went to check the front and gauges and had about 116-low side (approaching overcharge section on gauge) and about 120 high side; clutch not engaged anymore and didn’t cycle back on; did something happen when I turned on the rear AC? Pressure drop caused a switch to stop compressor? Started wondering if I had an electrical problem; let it rest overnight; the next day hooked up gauges and can #2 to low side in case a miracle occurred overnight; had about 86 psi resting static P so that should be enough to let the compressor run; turned on engine and AC (but not rear) and clutch engaged and spinning; looking like I was home free as I added can #2; low side P about 62 and high side about 175; low would creep up to above 65 when I swirled the can then back down; can #2 empty and now have about 24 oz in system; obviously clutch relay works and fuse not blown (fans on that same fuse too and they turned even when the compressor didn’t); then, warm air again!; this time though, clutch is still engaged and turning the compressor; pressures went up to over 120 low side and into red overcharge area of gauge and high side at about 125; when engine was turned off did not return to 96 psi static pressures; stayed at about 125 both sides but ambient air temp was 95 degrees and probably was 120 degrees under the hood of the hot engine; Disgusted, I disconnected everything; next day, hoping for another improbable miracle, went out and turned it on (without gauges) but got nothing but warm air; my question is: did I somehow slug the compressor and maybe break a reed valve when that can tipped over? Are those things that dang fragile? I’ve seen them turn the can upside down into the low side on those “how to” YouTube videos which I would never do! Could the low side reed valve be broken and when the compressor runs is the pressure backing up to the low side? Or, is something else wrong; the only in-line switch per my Honda shop manual is a triple function A/C Pressure Switch on the high pressure liquid line that cuts off the compressor if it goes below 28 psi or above 455 psi; it also turns the condenser fan on if the P goes above 220 psi and off if it drops below 220 psi; Magnetic clutch relay is working (at least sometimes), fuse must be good because fans are running; either I messed up or the compressor or clutch is defective but I am SOL because I’m shade tree and the warranty requires proof of flushing entire system by a pro shop, and it’s been over a year anyway; I just hate to be whipped by this; after a few weeks to get over the frustration, I could try a new compressor but it is a major PITA to get to in this minivan; getting it out from the top the Honda way by removing the alternator and pushing the radiator out of the way is tough; I have replaced several alternators in several cars and this is by far the toughest--a real pain; after seeing it done on a YouTube video, I may take it out of the bottom next time but I don’t like the idea of loosening and moving that frame member; I think I did a good job on the plumbing, everything is tightly sealed; just the charging with cans gives me fits; I think if I had one of those $5000 plus automated AC evacuation/charging cabinets I’d probably be driving around with AC now.

  • #2
    75 psi low side is around 73 deg, so not cool, 112 high side is around 93 deg. This page long description makes it hard to see what you have or haven't done. I'm not sure at this point if you have put the full correct charge in or not,
    Possibilities are you got air back in the system between evacuating and charging, you didn't purge the hoses of air between vac and charge, Gauges are off, you don't have the right charge,
    Unlikely you slugged the compressor with liquid.
    Anytime a compressor locks up, it likely put metal in the system somewhere.
    Turning on the rear air is a red herring,
    It seems to me you never got pressures anywhere near where they should be, high is too low and low is too high.

    Comment


    • #3
      Thanks for reply. The 75 low side and 112 high side with a full charge was when I had a possibly stuck open expansion valve. I replaced the expansion valve and the pressures improved to 62 low and 175 high even with just 12 oz of charge, about 1/3 full. It was improving even more with the second can when all of a sudden the low pressure increased greatly to 125 and the high side decreased to about the same, all the while the compressor was pumping.

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      • #4
        Also, i was very careful to always purge air from the lines for a couple seconds with the refrigerant. But it is possible air got in..

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        • #5
          Tx valves don't "open or close" they are a variable restriction. If the pressures were equal with the compressor turning then the compressor is bad.

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          • #6
            Originally posted by JMO View Post
            didn’t want to take evaporator (front) and evaporator (rear) out to flush, or flush all remaining piping; told him my plan and the Denso tech told me to drain 4.5 oz oil out of new compressor, put 3 oz in new condenser, and dispose of 1.5 oz; .
            So, re reading this, you drained all the oil out of the compressor, put some back in the condenser, and than ran it? What the heck was the compressor supposed to be lubed with?
            I'll never understand why you would want to drain oil, a little too much will cause a slight reduction of heat transfer, too little will destroy a compressor, which would you prefer?
            You already know the system lack oil because the old compressor seized.
            Last edited by Cornbinder89; 07-19-2020, 10:02 AM.

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            • #7
              Hi. Been reading your texts on other threads and I can tell you have a deep knowledge of and experience with AC issues. Therefore, I hated to read that you thought my new compressor is probably ruined because you are probably correct. The old compressor was empty when I took it off. Nothing leaked out of the openings when inverted. The new Denso compressor came pre-charged with sufficient oil to charge an entire empty system, so I understood. That being said, if there was already oil distributed in the system (except the new condenser and maybe a trivial amount in the new hi P vapor hose from compressor to condenser and the new low P vapor hose from evaporator to compressor) not draining some of the oil in the new compressor might have over charged the system with oil. My Honda shop manual tells you to drain the old compressor and subtract that amount drained from 7 oz. Whatever that amount is, drain that amount from the new compressor. It also notes: Even if no oil is drained from the removed compressor, don't drain more than 1 2/3 oz from the new compressor." However, I called Denso, and the tech I talked to (who said he had over 25 yrs experience) told me to drain 4 1/2 oz out of the new compressor, add 3 oz of that to the new condenser and discard the remaining 1 1/2 oz.. So I disregarded the Honda shop manual and listened to the manufacturer. I think the new compressor still had some oil left but I'm not sure. I just did what he said to do. Back to history, I thought the old compressor seized because I made a mistake and probably overcharged it with freon using one of those cheap little parts store charge hoses with a little gauge on it. I didn't have access to my real manifold gauges at the time. It cooled then for a day or two then locked up. It was a 21 year old compressor and had been noisy for several years. I had some black dirty crud around the compressor connections so I know some oil had leaked plus the connections were leaking some freon which I detected with my halogen detector sniffer but I never saw any actual oil around it.

              Comment


              • #8
                Originally posted by JMO View Post
                H. The old compressor was empty when I took it off. Nothing leaked out of the openings when inverted. The new Denso compressor came pre-charged with sufficient oil to charge an entire empty system,.
                No oil is why the old compressor packed it in. For an overcharge to damage the compressor it would have to be so much over that liquid refrigerant was making its way in the cyl of the compressor. Given that most compressors have the low side empty into the compressor sump to cool the compressor and return the oil, there would have to be so much refrigerant that it would stay liquid and not flash to gas on the hot compressor component's.
                The reason compressor oil type is dependent on what refrigerant is used, is because there are no oil control rings on an A/C compressor and the oil is soluble in the refrigerant. This means every time the charge leaks low enough to cause a problem with cooling, some of the oil has gone with the refrigerant. When you keep "boosting it back up" you replace the refrigerant but not the oil. It doesn't take long to run the system low.
                Some early compressors had a dip-stick you could place in the plug on the side of the compressor when evacuated, to check the oil level (York, Blissfield and some Sandens) or a level plug on the side GM A-6. Most newer stuff doesn't.
                If you put double the oil charge in, I doubt it would cause any damage, excess oil would pool in low spots like the receiver and bottom of the condenser. I am not recommending a double charge, but you would be hard pressed to do damage with slight too much oil. The excess would likely line the tubes of the condenser and evaporator, reducing the heat transfer, but doing no damage.
                Personally, I would left the oil charge alone, and once the system was vacuumed down, spun the compressor shaft to make sure it didn't have oil in the cyl, then recharged and let the system distribute the oil.
                Most new compressors made today have a very small sump for oil in the compressor, there is very little "excess" oil for the compressor to loose a little and still have enough. The older compressors, like the York, GM A-6 and Chry RV2 had a fairly large sump, and a way to check the oil.
                If I were servicing a system that lost its charge, after solving the leak, I would drain and refill the compressor with new oil to the amount spec'd for the system.
                The reason your old compressor had been noisy was low lube. I have a compressor on one of my semi's that came off a mid 60's GMC and is still working fine, 50 years old? or there abouts.
                Anytime a compressor has been run until it seizes, there is a good chance metal is in the system somewhere. Presume it to be so, until proved otherwise.

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                • #9
                  Yep. That sounds like what happened. Rookie mistakes made, but i appreciate education. This experience and education wont be wasted because I have an identical 2003 Odyssey (same generation) with only 130,000 miles so if it isn't damaged I will be working on it in the future even after this one goes to the scrapyard. It's good to learn on an old vehicle. When i have had old vehicles I learned auto repair with experience, but when i had new ones, I learned nothing. Even when this van was new, I was afraid to touch it other than oil changes. Besides, little goes wrong, and then there is the warranty. I'm still thinking about my next step. Redoing every thing I did is not appealing to me. Brand new condenser cant be flushed, so would need replacement, new hoses could be flushed, old lines too. Brand new evaporator I guess could be flushed, would have to come out to disconnect the TXV to flush properly. Rear evaporator I have read is a pain to get to for service and there is another TXV back there. I already have a pressure flush canister and a 60 gal air compressor so I have the tools. Another Denso compressor is $245 at RockAuto. They have UAC brand for $170.

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                  • #10
                    We all learn by making mistakes. I have always said, I can do it wrong, learn and do it over for less than paying for someone else to do it. But you have to be prepared for the doing it over part, and accept that it may cost you more, when you learn, but the knowledge will stay with you.

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                    • #11
                      Update; after 5 days I took the van out for its twice a week exercise (the first time since I worked on it) and while still in the neighborhood I turned the AC on just for the heck of it and I felt the engine draw down a little like the compressor engaged and it started immediately blowing cold air out!! I turned it off as soon as I felt the cold air come out. How about that? I think I have about 24 oz freon in there minus the little 2 second shots i wasted to purge air from the service line and the other manifold gauge lines. I dont know how much is lost when some vapor phase is released for that. It is possible I have at least 22 or 23 oz in there. I think I may try to add 8 oz (30 to 31 oz is a full charge). I will wait on the Mastercool tool i ordered to change the valve cores without evacuating the system. I put new cores in and got them to not leak but when i took my connections off, they leak a tiny amount. i dont dare tighten them anymore-afraid I will strip aluminum threads. I have checked and Honda doesnt sell a specific valve core. I guess they are universal. they might quit leaking after i do the manifold connection again. the pin could be cocked a little. At static pressure and with the caps on tight, my sniffer barely picks it up. Course the high side might leak more past the cap when pressured up.

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                      • #12
                        There are several types of valve cores, The std one like a tire uses is common, but there are several "high flow" types, so you will need to know which one you have. I have no list that tells me what your vehicle will be fitted with.

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                        • #13
                          Yeah, I dont know why they are leaking. They are the Murray Inc. kit from OReilly's that claimed it fits a 2000 Odyssey, contains two small and two larger cores and two small and two larger caps. The large cores are too large. The small ones exactly fit. The rubber gasket on the old OE cores seemed to be slightly wider than then new ones. They threaded in fine. After charging and removing gauge connections they leaked a bit, so tightened until they stopped. Had to use gauges again and afterwards they leaked some again. I tightened a little more but still leaked. I dont want to tighten any more. On my Uniweld gauges when opening the valve it turns with resistance at first-that's the part that is opening the hose, then it turns loosely about 1 turn before it contacts the valve core. Then you feel more resistance as it pushes the needle down. I watch the gauge as I turn and when I see it bump, I turn another 1/4 turn then stop. It should then be open enough. So I'm sure I didn't press the valve in too far.

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