Compressor noises

[TheUnicorn]

Hi all,

I need your wisdom...my mechanic is at a loss. We've replaced essentially all A/C components: drier, condenser, compressor and clutch, refrigerant pressure switch (on the back of the compressor), the clutch relay switch on the drier, and the evaporator and orifice tube. 8oz of oil added to the compressor. It holds vacuum. However, after happily blowing cold and running for 45 minutes, the compressor starts making a terrible sound, and the clutch face seems to be discoloring, assumedly from heat.

This is actually the second compressor this has happened to...we previously though the computer was bad, so we bypassed it, and presumed that bypassing the computer led to excessive wear on the clutch and compressor, causing the first failure. But we have since gotten the computer back in the loop (the actual problem was the refrigerant pressure switch) but the noise started happening to the new compressor as well.

Basically the entire system is new at this point.

No idea why this is happening. Anyone experience something similar? Am I missing something?

[CopperFiremist]

Did you replace the orifice tube?

[TheUnicorn]

Orifice tube was replaced with the evaporator before the previous compressor died. Do I need to replace it again?

[CopperFiremist]

I would pull it out and have a look at it.

[TheUnicorn]

So the orifice tube seems to be normal and undamaged, according to my mechanic. Any other ideas?

Much appreciated!

[MechBob]

what are the pressures when it is acting up

[TheUnicorn]

Gauges were not attached at that time, but about 20 minutes before the bad sounds started, they were 135-145 on the high side, and 29-30 on the low side.

[MechBob]

OK.Well,older A/C systems are actually simple.It would be nice to know if the compressor makes noise before the clutch starts disintegrating.2 ways the system can destroy a clutch,pressure too high,which theoretically is protected by one of the pressure switches/system.The other way is compressor mechanical failure.Can you spin either compressor over easily?Even the one that is mounted and charged can be spun,and any good A/C tech has done this and knows what it should feel like.Now to the compressor clutch itself.If the clearance between the plates is too large,it can cause a fast failure.Also,low voltage from poor wiring,bad relay,etc can cause failure.There is also a remote possibility of system being over pressurized intermittently, as it takes a bit for the switch and PCM to turn it off.Or the switch is stuck on.Or the PCM is bad.There is also a chance of intermittent over pressurized because the fan clutch is bad,or there is too much crap (weeds,pine needles,etc) between the condenser and the radiator. Which usually kills a fan clutch anyway. Good luck.

[TheUnicorn]

Well, the short version of the answer seems to be that I installed the orifice tube the wrong way. Evidently my mechanic didn't notice that either, so that was an expensive lesson to learn from another mechanic!

Thanks for the assists!