AC compressor replaced & charged, worked briefly

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2,789
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California, USA
I hung out with a friend today to help him finish up an AC compressor replacement in a 2005 Mazda3. It seemed like it was going well, aside from some tool issues, until we hit a snag. His description:
Quote:
The AC in my 2005 Mazda 3 stopped working 6 months ago. Finally got around to working on it: replaced the high pressure hose, then realized the compressor had seized. Just finished putting the new compressor in. I cleaned the system with solvent and put it under -30psi vacuum for ~an hour. Then charged it up, and it worked great! For about ten minutes. Then the AC started fluctuating in temperature from room temp to cold. Then I got a burning smell and it stopped cooling. The AC clutch is not engaging now. The low side of the ac was at 50psi when I charged it, and it's at ~150psi now (but the car is hot). Any ideas? I'm thinking it might be a stuck expansion valve. There was a bit of metal in the oil from the old compressor.
My notes: - We charged the system through the low side while the car was running with AC on (compressor engaged) up to ~45-50 PSI as measured by a cheap gauge/hose combo that screws onto the top of the R134A cans you get at auto parts stores. The AC was blowing cold when we were finished. - While on a drive with the AC running is when it started blowing warm again, and we got the smell he referred to. The smell could've just been spilled oil that finally got hot enough to burn off but the timing was quite coincidental if that's the case. - The "150 PSI" refers to checking the pressure using the same gauge, from the low side, after the car was shut off. I'm not clear on why the pressure read higher after the car shut off or whether that's a problem. But we tried on another car with working AC and got a similar reading, so maybe it's either normal or the gauge is screwy? Is the most likely scenario a clogged expansion valve due to debris from the old seized compressor? The only other possibility that comes to mind is an electrical problem but that seems less likely to me. I'm hoping for his sake that replacing only the compressor wasn't too big a mistake.
 
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15,879
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NE,Ohio
you normally have to replace other parts with the compressor or you will blow up the new compressor. Cheap bottle gauges are not very good. did your replacement refrigerant cans have oil in them? I'm guessing you blew up the new compressor with metal shavings etc from the old compressor that failed.
 
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25,815
Location
Upstate NY
You need to add the proper weight of R134a as listed on a sticker under the hood. You should not do it via pressure. What happened to the old compressor? If it grenaded then you need to flush the system and replace the orifice.
 
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beaver land EH?
5 things I see: (1) did you blow all the solvent out after solvent flushing the system (sans compressor)? (2) did you replace the orifice tube? (3) did you replace the dryer? (3) did you add enough compressor oil (and the proper type)? (4) did you add the proper amount of refrigerant? Q.
 
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22,478
Location
Apple Valley, California
if the compressor locked up it needs a condenser,dryer,expansion valve and maybe hoses if they are contaminated too. it defiantly needs all that now that a 2nd compressor has quit.the charge needs to be exact. no guessing as the refrigerant moves the oil.
 

rationull

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More details: - He did add oil to the new compressor. I wasn't present for this but he added based on the amount quoted in the manual and the amount that came out of the old compressor. - He did blow the solvent out of the system after flushing it. May not have been 100% complete, I'm not sure. I wasn't there for that part and the compressor he was using is pretty weak. - The compressor ran for a while because it took us a while to charge it today (tool issues). It was probably running (at lower than normal pressure) for 25-30 minutes or a bit more before we got it up to pressure. It sounded fine and the air was getting cooler as it got charged. - I don't think the new refrigerant had oil in it. We were charging based on pressure but also based on approx weight. IIRC the system takes something like 18 oz and we put in basically one 12 oz can and part of another one and stopped when the pressure looked good. - He did not replace any parts other than the compressor and a failed hose. - I don't think the new compressor is grenaded -- at least not completely -- because it still turns easily by hand. My best guess also is that this is caused by leftover debris from the old compressor. He's looking into getting an expansion valve thinking that maybe that's what's clogged but it's a shot in the dark at this point.
 

rationull

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Originally Posted By: Chris142
if the compressor locked up it needs a condenser,dryer,expansion valve and maybe hoses if they are contaminated too. it defiantly needs all that now that a 2nd compressor has quit.the charge needs to be exact. no guessing as the refrigerant moves the oil.
From the info so far though is it established that the new compressor has quit? It still turns fine by hand, so the problem could just be that the clutch isn't engaging for whatever reason (electrical, pressure?) right?
 
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Apple Valley, California
this is why ac repairs are so costly.theres no short cuts.from the original.post he did not even replace the dryer. the dryer is a dryer,storage tank and a filter all in one. not replacing the drier is much like putting a brand new engine in your car and putting your old used oil and filter into the new engine
 
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Hawaii
Did he replace the drier? Did he check for vacuum leaks using a vacuum pump? It should maintain vacuum for 30 minutes. If there is still refrigerant in there by using a manifold gauge set, his problem might be the thermal expansion valve. That should have been replaced too. Does it have vibrating sound near the glove box when AC is on?
 

rationull

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California, USA
We didn't do anything to try to check the clutch independent of the rest of the system yesterday. Unfortunately the electrical connection is pretty buried but that might be something to check as well. It is possible the burning smell was electrical. It did pull a vacuum for a while, and I think it held while the pump was off but I don't know if it sat like that or for how long with the pressure checked afterward.
 
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stl
Originally Posted By: Chris142
this is why ac repairs are so costly.theres no short cuts.from the original.post he did not even replace the dryer. the dryer is a dryer,storage tank and a filter all in one. not replacing the drier is much like putting a brand new engine in your car and putting your old used oil and filter into the new engine
This.
 
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8,598
Location
Florida
What compressor did you get? I once had to use "Compressorworks" brand on a 1999 Ford Escort, and every one of them failed after installation. The clutch simply never would engage. We had to send them back and get some other kind of compressor. That was a generic look-alike compressor, but rebuilt compressors can be just as awful. Anyway, if your mechanic didn't flush the system, replace the drier/accumulator, and replace the orifice tube/expansion valve you will never get a lasting repair.
 

rationull

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California, USA
Originally Posted By: artificialist
What compressor did you get? I once had to use "Compressorworks" brand on a 1999 Ford Escort, and every one of them failed after installation. The clutch simply never would engage. We had to send them back and get some other kind of compressor. That was a generic look-alike compressor, but rebuilt compressors can be just as awful. Anyway, if your mechanic didn't flush the system, replace the drier/accumulator, and replace the orifice tube/expansion valve you will never get a lasting repair.
Good question. I don't know what brand the compressor is but I'd put my money on the other parts at this point I think. Even if the new compressor has failed on its own it sounds like the other parts really should be replaced anyway.
 
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1,680
Location
CT
Originally Posted By: rationull
Quote:
There was a bit of metal in the oil from the old compressor.
I'm hoping for his sake that replacing only the compressor wasn't too big a mistake.
you most likely wasted the new compressor. If you didn't... yet, there's a good chance that metal debris is plugging up your condenser, and the filter/drier is probably holding a good amount, which WILL kill the new compressor. just a matter of time. whenever you have a compressor failure, especially a failure you know threw metal into the system, you have to clean it all out. the only thing you should reuse is the evaporator and lines. you need to flush them out real good. then with a new compressor, new condenser, new filterdrier and new Tx valve you pull a deep vacuum and make sure it holds, inject the right amount of oil then charge with refrigerant.
 
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1,680
Location
CT
this is also why a compressor manufacturer will not honor a warranty unless they have proof installation of the compressor was done properly, which is a good reason why you should pay and have it done by a licensed ac repair shop that will stand behind their work.
 
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