A/C STILL dead. Compressor #2 kaboom.
05-02-2005, 02:58 AM
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A/C STILL dead. Compressor #2 kaboom.
This just keeps getting weirder - and worse.
About a month ago josephsc nicely offered to host a "Socal A/C day" with access to his technical expertese and stash of r12 refrigerant. At the time, I was pretty sure my a/c compressor front seal was shot since I had previously replaced the clutch & pulley assembly (maybe 6-8 months ago) and gotten a nice "pssshht" of refrigerant at that time out the front seal. Figuring "what the heck, let's test it", we tested the system and it seemed to hold pressure okay so I figured maybe the front seal had re-seated itself over the time that had elapsed or something and was actually sealing okay now. We decided to put a test charge into it to see. Initially it worked okay but very shortly after activating the compressor and putting a can of oil and about two cans of refrigerant (noting increasing pressures in the low & high side lines as I should have), I got equal pressures in both the high & low pressure lines - not good. Turns out the shaft inside the compressor snapped.
I confirmed this today by rotating the pulley of the "dead" compressor and noting no suction or pressure at the line connection ports once I'd dropped it out of the car.
So today I got around to installing a used but "known good" compressor I bought off another Rennlister. I confirmed this compressor as good out of the car by slowly rotating the compressor pulley while simultaneously putting my thumb over each of the two holes at the connection points for the hoses. As it should have, one sucked and the other blew. Good deal. I cleaned it up and installed it along with new O-rings and a new receiver-drier. I then proceeded to "jumper" the clutch (as you're supposed to) and put 2 cans of r-12 oil into the system. All was good at this point. Once I started to add refrigerant, things got weird. Next thing I know the compressor isn't making any noise any more and I've got equal pressure once again in the high & low pressure lines. I can't believe this - what are the odds of snapping TWO a/c compressor drive shafts in a row? What the heck could cause this? Any suggestions? I really don't feel like going to the dealership and getting ***-raped for $1,500 or more to get this fixed.
Thanks all.
About a month ago josephsc nicely offered to host a "Socal A/C day" with access to his technical expertese and stash of r12 refrigerant. At the time, I was pretty sure my a/c compressor front seal was shot since I had previously replaced the clutch & pulley assembly (maybe 6-8 months ago) and gotten a nice "pssshht" of refrigerant at that time out the front seal. Figuring "what the heck, let's test it", we tested the system and it seemed to hold pressure okay so I figured maybe the front seal had re-seated itself over the time that had elapsed or something and was actually sealing okay now. We decided to put a test charge into it to see. Initially it worked okay but very shortly after activating the compressor and putting a can of oil and about two cans of refrigerant (noting increasing pressures in the low & high side lines as I should have), I got equal pressures in both the high & low pressure lines - not good. Turns out the shaft inside the compressor snapped.
I confirmed this today by rotating the pulley of the "dead" compressor and noting no suction or pressure at the line connection ports once I'd dropped it out of the car.So today I got around to installing a used but "known good" compressor I bought off another Rennlister. I confirmed this compressor as good out of the car by slowly rotating the compressor pulley while simultaneously putting my thumb over each of the two holes at the connection points for the hoses. As it should have, one sucked and the other blew. Good deal. I cleaned it up and installed it along with new O-rings and a new receiver-drier. I then proceeded to "jumper" the clutch (as you're supposed to) and put 2 cans of r-12 oil into the system. All was good at this point. Once I started to add refrigerant, things got weird. Next thing I know the compressor isn't making any noise any more and I've got equal pressure once again in the high & low pressure lines. I can't believe this - what are the odds of snapping TWO a/c compressor drive shafts in a row? What the heck could cause this? Any suggestions? I really don't feel like going to the dealership and getting ***-raped for $1,500 or more to get this fixed.
Thanks all.
05-02-2005, 03:22 AM
#3
http://www.babcox.com/editorial/ic/ic50350.htm
Another reason for flushing is to remove residual oil from the system. This is necessary when retrofitting an older R-12 system to the new ozone-safe R-134a refrigerant, but it’s also a good way to make sure the system contains the right amount of oil. Simply adding oil to the system to replace that which has been lost is a guess at best, because there’s no way to know how much has been lost due to leakage. Estimating a couple of ounces here and there for replacing an accumulator, receiver/drier, condenser, compressor or hoses is not a very accurate means of determining how much oil needs to be added to the system when it’s recharged with refrigerant. Flushing gets rid of all the oil so the exact amount specified by the vehicle manufacturer can be added back to the system.
What happens if there’s too little or too much compressor oil in the system? Not enough oil in the system will reduce compressor lubrication and may lead to premature failure. Too much oil in the system can puddle in the condenser and obstruct the flow of refrigerant causing a drop in cooling performance.
Another reason for flushing is to remove residual oil from the system. This is necessary when retrofitting an older R-12 system to the new ozone-safe R-134a refrigerant, but it’s also a good way to make sure the system contains the right amount of oil. Simply adding oil to the system to replace that which has been lost is a guess at best, because there’s no way to know how much has been lost due to leakage. Estimating a couple of ounces here and there for replacing an accumulator, receiver/drier, condenser, compressor or hoses is not a very accurate means of determining how much oil needs to be added to the system when it’s recharged with refrigerant. Flushing gets rid of all the oil so the exact amount specified by the vehicle manufacturer can be added back to the system.
What happens if there’s too little or too much compressor oil in the system? Not enough oil in the system will reduce compressor lubrication and may lead to premature failure. Too much oil in the system can puddle in the condenser and obstruct the flow of refrigerant causing a drop in cooling performance.
05-02-2005, 03:24 AM
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Joe has an EPA certification; I guess you can get it in Mexico or somethin'. I may convert over to Freeze 12 if I run out of r-12 (and out of compressors!)
My theory is that possibly I froze up the expansion valve (since I didn't have the system "shop-evacuated", only evacuated by me with my teeny little hand pump to make sure the system held vaccum prior to installing the receiver-drier and charging. If this resulted in residual moisture in the system, I imagine it could theoretically freeze up the expansion valve. If this happened, could it cause a compressor failure?
My theory is that possibly I froze up the expansion valve (since I didn't have the system "shop-evacuated", only evacuated by me with my teeny little hand pump to make sure the system held vaccum prior to installing the receiver-drier and charging. If this resulted in residual moisture in the system, I imagine it could theoretically freeze up the expansion valve. If this happened, could it cause a compressor failure?
05-02-2005, 03:26 AM
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05-02-2005, 03:26 AM
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Thanks Kevin, but I'm reasonably sure the system had no oil in it prior to the installation. The compressor was drained out and I wanted to be certain that the system had adequate lubrication prior to adding the refrigerant. The weird thing was when I added the first can of oil, the pressure came up to about 20 psi on the low and about 40 on the high side - so far so good. With the second can of oil it was about 30 psi and 60 psi. Also fine I guess. Once I started adding the refrigerant was when stuff went weird. Coincidence maybe?
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05-02-2005, 03:33 AM
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On my 924s, I had to do it at the Schrader valve either on or right next to the compressor (I don't remember now). The one on the firewall did not work.
Was the clutch still engaged?
Was the clutch still engaged?
05-02-2005, 04:02 AM
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Just very weird - I really don't want to delete the a/c system. That always seemed like a cop-out to me. Porsche put 'em on there and they should work. The entire weight of the a/c system is what? 40 pounds maybe? Is that really worth it? Nope. I can just lose 20 pounds and run with about 4 less gallons of gas - it'll do the same thing. Besides, this car is my daily driver right now and it's getting hot around here. I really want to get the a/c system functional.
I never did see anything in the receiver / drier. I did (when the drier was out) hook up a hand vacc. pump to one side and then the other. Maybe I should try blowing out the system with compressed air or something (?)
I noticed that the clutch had done something strange on the old compressor (the dead one) - it had kind of fused in the "shut" position. I didn't see how much effort it would take to loosen it and allow the clutch pulley to turn independently of the main drive shaft. Maybe I'll look at that tomorrow.
I noticed that during tonight's adventures that the clutch pulley similarly didn't disengage a couple of times. I had to shut the car off, pull the battery cable and gently pry on it with a flat-blade screwdriver. Once I reconnected the battery and restarted the car, the pulley turned freely on the compressor when it wasn't engaged and otherwise worked fine. Crud in the clutch plate maybe? I cleaned it pretty good, but I suppose anything is possible.
I'm (unfortunately) running out of ideas. I think it's time to replace the compressor (again). I'll confirm at that time whether the shaft is indeed snapped, but I kind of have a hunch given the steady "30psi / 30psi" reading I'm getting on the low/high sides and inability to add any more freon. I guess it'll be a good idea to replace the expansion valve also and I'll for sure take the thing in and have it professionally vaccummed out and leak-tested before I do anything further.
This was a bad night in the garage - $50+ worth of refrigerant, $30 worth of oil, $200 in a compressor, and about 8 hours of my time screwing with it. I'll probably end up getting a Sanden unit like I did on the 944 - they're excellent compressors and it'll be new, not rebuilt or used. Less to go wrong that way. That and a new expansion valve should run about $600 though, plus about $100 on a leak-test and vaccum (and another receiver-drier & o-rings). Grrr. It shouldn't be this difficult. Something is weird. Maybe changing the expansion valve will solve problems although I hear it's a royal bitch to get at on the later cars (including the turbos). What's new? EVERYTHING is difficult to get at on the turbos!
Well, there's another 2-month delay on getting the Callaway running. . . I have a feeling this will cost about a grand when all is said and done. It may dash my ideas for going to 944fest also - I sure as hell am not making that journey without working and reliable a/c!
I never did see anything in the receiver / drier. I did (when the drier was out) hook up a hand vacc. pump to one side and then the other. Maybe I should try blowing out the system with compressed air or something (?)
I noticed that the clutch had done something strange on the old compressor (the dead one) - it had kind of fused in the "shut" position. I didn't see how much effort it would take to loosen it and allow the clutch pulley to turn independently of the main drive shaft. Maybe I'll look at that tomorrow.
I noticed that during tonight's adventures that the clutch pulley similarly didn't disengage a couple of times. I had to shut the car off, pull the battery cable and gently pry on it with a flat-blade screwdriver. Once I reconnected the battery and restarted the car, the pulley turned freely on the compressor when it wasn't engaged and otherwise worked fine. Crud in the clutch plate maybe? I cleaned it pretty good, but I suppose anything is possible.
I'm (unfortunately) running out of ideas. I think it's time to replace the compressor (again). I'll confirm at that time whether the shaft is indeed snapped, but I kind of have a hunch given the steady "30psi / 30psi" reading I'm getting on the low/high sides and inability to add any more freon. I guess it'll be a good idea to replace the expansion valve also and I'll for sure take the thing in and have it professionally vaccummed out and leak-tested before I do anything further.
This was a bad night in the garage - $50+ worth of refrigerant, $30 worth of oil, $200 in a compressor, and about 8 hours of my time screwing with it. I'll probably end up getting a Sanden unit like I did on the 944 - they're excellent compressors and it'll be new, not rebuilt or used. Less to go wrong that way. That and a new expansion valve should run about $600 though, plus about $100 on a leak-test and vaccum (and another receiver-drier & o-rings). Grrr. It shouldn't be this difficult. Something is weird. Maybe changing the expansion valve will solve problems although I hear it's a royal bitch to get at on the later cars (including the turbos). What's new? EVERYTHING is difficult to get at on the turbos!
Well, there's another 2-month delay on getting the Callaway running. . . I have a feeling this will cost about a grand when all is said and done. It may dash my ideas for going to 944fest also - I sure as hell am not making that journey without working and reliable a/c!
05-02-2005, 12:01 PM
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If you can recommend one for that price, please let me know! The cheapest I've found is about $150 and that's just for a leak test and diagnosis. . .
I have a new theory but am on the way out the door for work - I'll post more later to see if it makes sense.
I have a new theory but am on the way out the door for work - I'll post more later to see if it makes sense.