'94 Cadillac, bad compressor or clutch?

atikovi on Sun May 15, 2011 5:26 PM

Year: 1994
Make: Cadillac
Model: Fleetwood
Engine Size: 350
Refrigerant Type: 134

I have not used the a/c in the car for 2 or 3 years so when I tried it today it didn't work. Hooked up the gauges and it showed 20psi so I figure it was low but at least not empty so there isn't a leak. After connecting a drum of 134 the low side went up to 65psi and I turned on the a/c. I could feel the engine rpms drop quite a bit more than usual and saw the compressor barely turning over, maybe once every 2 seconds and starting to smoke. Is this more likely a bad compressor or the clutch? I'm thinking compressor since it's struggling so hard to turn over while the clutch is engaging fine if the engine speed drops that much.

GM Tech on Sun May 15, 2011 6:17 PM

Quote
Originally posted by: atikovi
Hooked up the gauges and it showed 20psi so I figure it was low but at least not empty so there isn't a leak.

Non-truer words have never been spoken....

You have a leak - period

You tried to run a dried out compressor with little or no oil in it and now it is seizing- the clutch is probably coated with oil/grease from the likely shaft seal leak you have.

Now what to do-- if you want to try and save the compressor- (it maybe too late) you can fix the leak- put in a new shaft seal - or a new compressor if you have not any compressor tools.. Then get oil to the pump pronto.....

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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......

Edited: Sun May 15, 2011 at 6:21 PM by GM Tech

atikovi on Sun May 15, 2011 8:03 PM

I bought the car 8 years ago and never messed with the A/C and I'm pretty sure it worked 4 years ago. So after 8 years to have the charge at 20psi is considered a leak? This is an older car and I assume not as tight as the late models and I always remember seeing ads in the paper years ago in the spring for A/C top up services so aren't they expected to loose a little charge, especially after 8 years? The clutch was smoking so I'd probably replace the whole compressor.

GM Tech on Sun May 15, 2011 9:38 PM

20 psi static pressure equates to about 99% refrigerant charge loss....so yes you have a leak. Topping off systems with known leaks without fixing them is considered illegal and you can loose your refrigerant handling license.

-------------------------
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......

NickD on Mon May 16, 2011 9:35 AM

Ha, lose what license or certificate, this vehicle was retrofitted to R-134a that can be purchased by anyone without a certificate except in the state of Wisconsin. Even my grandkid can buy a can of R-134a in Illinois.

Speaking about Illinois, drove my wife down there last week on US 14, an old federal two lane road I haven't been on in years. When we came to the border, what happened to all those stores? Wisconsin side was loaded with beer stores to sell beer to Illinoisans over 18, in Illinois, had to be 21 to buy beer. Illinois stores were loaded with margarine stores for Wisconsinites, as selling margarine was illegal for sale in Wisconsin. Just an empty field now, but at least expected to see one store with a big sign, Buy your R-134a here certificate free!

EPA lets you dump in a can of R-134a to find those leaks and waste it. Its their logic, better to lose one can than an entire system full. Can even do that if this system stayed R-12! Sure don't want to do that with a can of R-12, would need a second mortgage on your home, and that you need a certificate for.

This car is a Fleetwood, kind of lost interest in that car after 1978, not only unsolvable disk brake and steering problems, putting in a Chevy engine was way too much. Would like to see a picture of the underhood, is the compressor still on top? And a large evaporator box on the right hand side. If it is, a very simple system to find leaks on. Not like the DeVille of that era with the evaporator hidden way under the dash and the compressor dragging on the pavement.

Sure can't find a leak with only 20 psi in the system, could only have a couple of tablespoons full, and that's vapor, not liquid. But I agree, that leak has got to be found and repaired. And really check of any oil leaks. If anything like my old 78, they really haven't change that much with that body style, just a lot more plastic and a lot less metal, a very simple system to work on. Just about the only thing I miss about that car.

JJM on Sat May 21, 2011 12:04 AM

The business model for those "top-off" shops is excellent... steady cash flow for regular "top-offs" which leads to a complete system replacement when the compressor runs dry. The "top-offs"certainly take less time than diagnosing and repairing the leak. And yes, topping off a system with known leaks is illegal, but that doesn't stop lesser shops.

Besides, with refrigerant prices what they are, better off fixing the leak. Fixing a leak is a lot cheaper than replacing the compressor, condensor, OT or TXV, accumulator or dryer, lines with mufflers, flushing the rest of the system out.

Joe