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AC comp. problem ?

kourso on Thu October 08, 2015 10:25 PM User is offline

Year: 1994
Make: Chevrolet
Model: Pickup
Engine Size: 5.7L
Refrigerant Type: 134a
Ambient Temp: 88
Country of Origin: United States

My 1994 Chevy pickup AC comp. clutch started smoking & the clutch was scalding hot.
After it had cooled I tried engaging the AC comp. clutch and i didn't see it or hear it engage.
I suspect the clutch may be burnt up but not sure. Would it be worthwhile attempting a clutch replacement on a 4 yr. old AZ or Oreilly rebuilt compressor? Prior to this issue the AC system had a constant freon leak which I was unable to find even with a Robinair freon detector & uv black light. I have done AC comp & evap. replacement work but never disassembled an AC clutch.
Is there anything that I can do to check the compressor internals with the clutch not engaging?
And I do have an AC manifold gauge set & vacuum pump.
Please give me some professional advice & repair options.
Thank you

GM Tech on Fri October 09, 2015 8:33 AM User is offline

Can you turn the clutch driver 360 degrees by hand? Does it catch, stop, or frozen in place? I suspect it is seized due to massive internal damage due to running low on refrigerant due to your leak. The worst thing you can possibly do is run any compressor with low refrigerant, because the refrigerant circulates the oil. R-4 compressors are the worst example of this because they and 134a do not get along well. Numerous R-4s have seized for the very reason I have stated above. Even if compressor turns, clutches will not last once they've been smoked. The surfaces work harden and will constantly slip under load. Sounds like time for a new compressor, and never let system run with less than 3/4 charge again.

Check orifice tube (behind left turn signal) for debris- this will be a tattle tail indicator of your issue(s).

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

kourso on Fri October 09, 2015 9:32 AM User is offline

Actually I was adding 1/2 can of freon when the clutch smoked ?
So I don't know if that caused this to happen ?
I have been stumped trying to find the leak. I still think the comp. shaft seal or the evap. core could be the leak source.
I have checked all hoses & fittings inc. the receiver/drier with the leak detector & soapy water. I just couldn't find it.
I will try to turn the compressor & possibly pull the orfice tube as suggested. How difficult to replace the clutch & what tools/cost?
Also exactly what parts ? Clutch & clutch coil only ?
Thank you very much for your assistance.

kourso on Fri October 09, 2015 9:36 AM User is offline

I thought the cycling switch was the lo suction protection for the compressor ?
Shouldn't that prevent lo suction press. compressor damage ?
The cycling switch had been functioning well.

GM Tech on Fri October 09, 2015 11:28 AM User is offline

The system will run with as little as 5% of required refrigerant in it. Proper oil circulation needs 75 % or better charge to not cause a lube problem. You have an evaporator freeze protection switch (cycling switch on A/D). NOT a low charge protection switch. It is a NO CHARGE protection switch, just not a LOW charge switch!

You can "borrow" needed clutch tools from Autozone- but I'd hesitate to say, your compressor is toast. If it slipped while charging- were you inducing liquid (can upsidedown?) If so, no oil was being sucked into pump- and you flushed liquid refrigerant through your compressor- drying it out- void of oil.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

kourso on Fri October 09, 2015 11:40 PM User is offline

GN Tech
My freon charge can was upright when the compressor clutch was smoking. I did give thought to the possibility of the freon can being upside down and introducing liquid to the compressor. I am baffled as to why it malfunctioned right then ?
As I was adding some freon.
I will have to try turning the comp. by hand. Again I just can't pinpoint the freon leak.
I thank all of you for helping me on this fantastic forum !

Cussboy on Sat October 10, 2015 8:10 AM User is offline

We had that R4 compressor and R134a in our 1994 Suburban with same engine. Yeah, mine had dual AC which is problematic in its own right, but my R4 compressors in that (and in my 1988 Suburban with R-12) lasted less than three years each (I concede that I'm in Arizona), in each case the leakage was through the compressor body, never had one seize.

If you go forward with the repair, only get a NEW compressor, not a rebuilt. And realize that the accumulators on these oftentimes like to pull off the threads of the evaporator connections, just a poor design not improved until later on.

I will add that the 1994 Suburban was factory R134a, and did cool real well. In general, I'd say that the AC on our 2005 Yukon is designed much better, even though the compressor is low as opposed to high on your truck.

Dougflas on Sat October 10, 2015 9:54 AM User is offline

If you think your compressor has a shaft seal leak,reove the belt and place a shower cap or plastice bag around it and tape it shut. go back 6 to 8 hrs later, poke a hole in the bag and try the leak detector again. Also, let's not fforget that leak detectors' sensors lose sensitivity and should be replaced when a loss of sensitivity occurs. I just replaced the sensor in a Tek-mate and it made a world of difference.

wptski on Sat October 10, 2015 1:37 PM User is offline

Quote
Originally posted by: Dougflas
If you think your compressor has a shaft seal leak,reove the belt and place a shower cap or plastice bag around it and tape it shut. go back 6 to 8 hrs later, poke a hole in the bag and try the leak detector again. Also, let's not fforget that leak detectors' sensors lose sensitivity and should be replaced when a loss of sensitivity occurs. I just replaced the sensor in a Tek-mate and it made a world of difference.
Was it the newer black case style?

kourso on Mon October 12, 2015 12:28 AM User is offline

Does that apply to Robinair 16600 electronic leak detector, the detector tips on these lose sensitivity and have to be replaced ? I am not sure on this type? I will do as you instructed, seal a bag over the compressor clutch or whole compressor to test for a leak.
I really appreciate all of your great help & ideas on this forum.
I have to conclude these old model R4 AC compressors are not very durable and prone to leakage.
Thank you very much

kourso on Tue October 13, 2015 2:29 AM User is offline

Ok guys
I tried grabbing around the clutch pulley & it wouldn't turn but maybe a 1/4" either way.
And when I shake the compressor I hear something rattling inside !
So I know this thing is shot. I am sure I don't need to pull the orfice tube now to find out.
Is a (new) Santech brand ok?
Thanks

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