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I keep blowing-out the compressor shaft seal

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  • I keep blowing-out the compressor shaft seal

    I am having problems and am in need of some advice as to what maybe the problem. I have blown-out two compressor shaft seals while trying to charge the system. From the beginning of the charge it was difficult to add to the system even when it has been evacuated. I tried to add part of the can to the high-side first, but did not seem to want to go in so I started from the low-side port. It was slow to go in but did and at the end of the second can the shaft seal blows-out. The high-side pressure reached a max at about 210psi while the low-side was about 30psi before the seal let go. This has now happened to me twice any help would be appreciated as to what may be the problem.

  • #2
    Welcome Tim: What is this vehicle would help so please add that and any history of why you are working on it at all.
    Lost without some info like, did it even hold a vacuum for at least 1/2 hour? Might not have or system capacity so little you can't get much in if using 12oz common cans of refrigerant.

    Need to know if you have replaced shaft seal or is this a remanufactured compressor first time attempted would help too.

    IMO, high risk with either. So you did get likely 24 oz in thru low side - should do that was gas only not liquid while running or it could choke it.

    IDK still need more info. Seals are a leak spot more than a blow out item as almost all have a pressure relief failsafe for wild overcharge or over pressure which is much higher than the 30/210 pressure you posted,
    MetroWest, Boston


    • #3
      Make and model of the compressor would be a help. I have no luck replacing seals on some, other I have no problem. Some require a shaft protector when sliding the seal into place. If you don't have all the right tools it can be a nightmare to do.


      • #4
        Internal wear may have made the shaft to fall or rise, renedering shaft seal replacement useless and a waste of money. I suggest replacing the compressor.


        • #5
          The vehicle is a 1988 Honda Prelude 2.0Si with 4-wheel steering and the compressor is a Matsushita/Panasonic NL1300AA4.
          A little history-I replaced the original compressor with a remanufactured one and changed from R-12 to R-134a. After I charged the system it would cool on warm days but shut-off on hot days after running for awhile. A red light would appear on the AC switch indicating that there was a difference in rpms between the crankshaft and compressor that lasted more than 3 seconds. I don't drive the car much so I lived with that condition until this summer when I tried to fix it by adding Freon. The gauges showed the low-side about normal 30psi but the high-side was lower than normal not rising above 150psi. I blew-out the shaft seal the first time. I took both compressors in to be rebuilt and after putting one back in tried to charge and blew the second one.


          • #6
            Oh man - getting lousy info to nothing for new for this car.

            For now just a question since using High Side presumably into a well held vacuum (engine off) would draw in most of a small 12oz can if you played temps, warm can, cool engine.

            Alone not the issue as retrofit fittings can be so misadjusted they totally leak or don't work especially if using the original Schrader pushed by the new fitting or OE Schrader removed using the 134a size alone available that way.

            Reviews on rebuilding these were the lowest of all lows! Not encouraging. In my searching around found it was used in other models totally so all hope for new not lost quite yet.

            Just some memory of assorted Hondas this old up to some a good bit newer the belts were manually adjusted on at least some subject to being left too lose for the light you saw or compressor choked even charging into a running system with can upside down - liquid not suggested.

            Who retrofitted this and was it totally done or just a quick kit? What oil used and was all mineral removed or some left in you can if you used Ester but only holds 5 oz oil total.

            Bit lost and feel for you. Quite a few usually Civics were real happy at less than some standard of 80% max charge of 134a of the known R-12 amount and behaved perfectly at as low as 65%.

            Nacho chimed in that shaft would be a reason if worn new seal or not would be the weak link. Jeez - rebuilders? How much can they really test for pressure which should blow out or in car shut down now thru high pressure switch added many were not.

            One more question - do you know the original failure and why?
            MetroWest, Boston


            • #7
              Yes the system would hold vacuum and when I tried to add thru the high-side and it didn't take any I later thought that the condenser might be the problem. I removed the original Schrader and only use the aluminum 134a adapter valve.
              I did the retrofit and followed the procedure flushing system components and replacing the compressor, receiver/dryer and expansion valve. Then filled with Ester oil containing UV dye.
              The original failure was some years ago and at that time I thought that the pressure switch blew-out spraying oil all over that area. Now I know that the switch would disengage the clutch. So it could very well have been the shaft seal on the original failure.
              What do you think of the idea that the condenser is restricted or partially blocked?


              • #8
                Was engine running when touching high pressure port for charging? Never do that.

                Oil: How much is in this thing? It's very easy to lose track and compressors will choke on it as they can't compress a liquid unknown if it would release pressure or break it in some way perhaps beyond possible repair as a core?

                Is a shaft seal the weakest part to take the "hit" if you follow me? I don't know is the only answer. Oil overcharge would usually puddle at bottom of a condenser the original should if tight blow out or flush out. The HE ones if installed when retrofitted really don't and just toss those like a bad filter or are just a restriction.

                New or remanufactured compressors should/must be turned with oil on bench first many times for the period of time when engaged and NOT charged enough to move oil take that for maybe only a minute or so or burn out right away! Heat or pressure that relief valve would blow oil all over the place and cause the entire job to fail new parts and all. The type of spring loaded pressure relief valves do not always reset to seal nor on time to save anything.

                I'm worried you are overloaded with oil, unlucky with new compressors and your aluminum high side port isn't cooperating with your Acme fitting I've had trouble with and another gauge set works not sure exactly why just poor fit probably.

                It's trouble. A set back puts you back worse than when you started. Been a while since retrofitting now and any if holding a vacuum would liquid charge engine off into vacuum thru high side to be part way there before running it at all which you couldn't.

                IDK - what do you wish to do? I think I'd have that compressor off to see if I can even feel it compress and not sure you can do that while installed on this? Tight in there as many are and don't think you can go thru the wheel well on these - been a long time but think it's metal not plastic you can remove to get at it?
                MetroWest, Boston


                • #9
                  I have a similar issue with my classic 1972 Chevy Chevelle SS 454. It has original factory air. I had the system charged with R12 and that lasted 1 day. Oil all over engine compartment originating from the compressor front seal. Purchased a rebuilt compressor and that leaked (worse) oil as well. Had the original compressor rebuilt and that lasted less than a week. Oil all over. Purchased a replacement compressor and dryer from NPD and charged with R134. That lasted a couple days. Front seal blown and oil all over the place. Are you counting the number of compressors? The installs were done at two different shops with experienced techs.


                  • #10
                    If you had it charged and it lasted one day, either they didn't check for leaks, before hand and it would have to be a big leak, or it is over pressurizing and blowing off the relief on the compressor.
                    While the face seal design can leak a little, I doubt 4 bad compressors, Stop throwing parts at it and do some real diagnosis
                    Without pressure reading while running there is not much we can do. Anybody who can't find a leak that drains the system in one day shouldn't be working on A/C.



                    • #11
                      Eeek are these places helping you with losses? Hope so.

                      Highly desirable car would think they'd really check it out before giving it back. Rebuilts are a problem IMO but 3 is pushing it.

                      What do you have for a fan? Should be I think 5 blades and a thermostatic clutch non A/C might have come with fixed 4 blade?

                      Cutches have been substandard good brands of new this would have an exposed spring in front a cheapo would roar hot or cold actually would work well not a nice sound.

                      If hot enough it's supposed to blow out but stop those sometimes reseal or not.

                      Pressures are a must post what found if you know. Failsafe isn't saving this disaster THEY SHOULD KNOW as Corbinder89 said or not be doing A/C at all IMO too,
                      MetroWest, Boston


                      • #12
                        The A-6 compressor is built with selective fit parts to tight tolerances'. It is its strength and weakness. If the close tolerance is not maintained, they will not last, but even when they leak due to poor fitment, it takes a season or more.
                        Their are special fixtures and tools to assembly correctly.
                        The shaft seal area only sees as much pressure as the low side, which is at its highest when the compressor is shut down.
                        It sounds more and more like the high side is too high and relief is opening, or the clutch is slipping to the point it gets so hot it melts the rubber in the seal.
                        Properly assembled and run with the right amount of lube, they should last a lifetime with occasional seal replacements.


                        • #13
                          Discussing this with the owner of the last shop, he indicated they pressurized the system for a few hours and no leaks. Added freon and tested both high and low end. No leaks. They did other test, but I didn't go into details with him. They kept it overnight and tested it again the next day. No leaks. I picked it up the third day and drove it home and tested on the way. It seemed to work ok. A few days later I went to a cruise night, which was a hot and humid day. I kick the air on and cool for 10 seconds and then hot air. The fan belt start squealing from being oil soaked. All I want is my A/C to work. FRUSTRATING!


                          • #14
                            I'm afraid we are not going to be able to provide much help. This forum can help those that are doing the work. Where as you are not, and don't know what exactly was done or not done, what the pressures are and stuff like that.
                            The most we can do is some general info.
                            Was anything changed from stock? does it have the stock cooling fan and shroud at the radiator?
                            What is the condition of the condenser? was the desiccant changed in the VIR if that is the system, if not was the drier charged?
                            A/C work isn't frustrating, but isn't tolerant of cut corners and incomplete servicing.
                            It is a free floating, balanced system, Change any one thing (poor heat rejection at the condenser, for example) and the whole system changes and reacts to the added heat in the system.
                            If the people you have doing the work don't understand the compression refrigeration cycle, and just chase things they can "see" like the oil loss, they will not be able to solve the problem.
                            Edit: I see a drier was replaced, that is good.
                            Last edited by Cornbinder89; 08-28-2022, 10:38 AM.


                            • #15
                              As I indicated earlier, the vehicle was shipped with factory air conditioning. So, all the A/C required components are there including correct fan, fan clutch etc. That doesn't mean they all function correctly. I'll need to research this a bit more. What I was hoping to find here is a direction or thoughts to look at or insist my shop review.


                              • #16
                                Ok, we've been down that road and then find out the orignial fan set up was replaced with an electric fan or some such, which is why we have to ask. A condenser can't do anything if it doesn't have air flow over it.
                                Pressures while running the a/c are critical to pointing where to look.


                                • #17
                                  OK, that info helps. Fan clutches IMO stink even some good known brands. Test those most will not coast when spun by cold (engine cold overnight or many hours) then drive it just to get it warm hot thru radiator.

                                  Shut down for a while it shouldn't coast doing that.

                                  I mean you spin it and can't make blades coast like a plain bearing rather stop part of one revolution.

                                  Open windows many cars/trucks you here it roar a bit at peak need is a warm/hot day drive then stop like at a traffic light first to go it should drag I notice good ones or not.

                                  If you feel and don't find an exposed bi-metal spring that makes them grab. Some without will too not as fast or just grab more all the time are power loss things then.

                                  By rights if moving along say over 40MPH the air thru grille will allow it to coast again saving power loss and the noise/feel annoying to me.

                                  IDK most in box new say do NOT turn upside down (I never have if off) may leak oil out??

                                  A 454 or not this should behave like that.

                                  I've owned 100s of cars you get to know what to expect most to flip a few I kept for so long - done but got to know what to expect models mostly popular so called American cars (have been jointly made where or parts lots older than this - owned many older than this would put the better fan on from a junk if non A/C didn't come with them work better anyway.

                                  That's why they are called a clutch if not temp sensitive they stunk and worked well for about 5 years toss for another new either A/C or not the roaring would quit I have one now OE clutch but is 26 years old A/C just refuses to be normal parked hot then in traffic output temps way too high and freezes me out if moving along.

                                  I also don't have to fix that or use it at all temp gauge for engine never moves super HD Chev truck all items extra cooling ordered new all still there didn't rust out where I am too bad fixed some - others "Winter" cars the best keepers don't get out much or at all in extremes that ruin cars even too much sun!
                                  MetroWest, Boston


                                  • #18
                                    You said they pressure tested the system. The system should be vacuum tested. Sometimes a system will show ok when pressure tested but, will leak when vacuum tested.


                                    • #19
                                      As part of testing along the way YES. Leaks can be one way. Know that "full vacuum" > "sea level" is sealing OUT just 14.7 Psi of pressure vs pressure in operation spikes well over 200 (R-12) not sure blow-out valves at or near 350 Psi. That's also HOT so if shop is doing this what did the seals look like AFTERWARDS? Melted?
                                      MetroWest, Boston


                                      • #20
                                        Relief valves are around 425 psi, I haven't seen lower for R12 but for either it is a fair bit above operating pressure in the hottest weather.
                                        They are there to protect the system and prevent burst hose.
                                        System shouldn't exceed 395-400 psi ever.