Automotive Air Conditioning Information Forum (Archives)

torqueaddict on Sat June 28, 2014 7:20 PM

Year: 1972
Make: Buick
Model: Skylark
Engine Size: 455
Refrigerant Type: 132a
Ambient Temp: 90

Hi. I have a 1972 Buick Skylark. I just got my AC running after not running for many years. A shop professionally did this and it does blow cold.

After running the ac for 15 mins or so, the belt no longer can turn the compressor pulley. If I turn off the ac it will turn again. The pulley gets hot enough to burn my hand but maybe that's because of the slipping?

If I let it cool down it works again but once it gets hot the same thing happens again. This is a new, correctly adjusted belt.

Thoughts?

thanks in advance!
-Dan

Edited: Sat June 28, 2014 at 7:21 PM by torqueaddict

TRB on Sun June 29, 2014 12:30 AM

Bad compressor or over charged system.

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torqueaddict on Sun June 29, 2014 9:31 AM

Thanks!
Do you think it could be the compressor bearing?

Edited: Sun June 29, 2014 at 9:32 AM by torqueaddict

wptski on Sun June 29, 2014 10:00 AM

There is a ball bearing in the compressor pulley but the only time that it's in use is when the A/C is OFF or cycled OFF. When the A/C is running and the clutch is engaged the bearing turns with the clutch plate. If the belt is removed the pulley should turn freely.

torqueaddict on Sun June 29, 2014 10:07 AM

Thanks that makes sense.

Can the clutch wear out and act this way?

I know those can parts can be replaced without opening up the system and they are cheaper than a compressor.

wptski on Sun June 29, 2014 11:08 AM

Quote
Originally posted by: torqueaddict
Thanks that makes sense.

Can the clutch wear out and act this way?

I know those can parts can be replaced without opening up the system and they are cheaper than a compressor.
If your clutch plate gap is too large, you can have slippage which causes lots of heat which they claim can destroy the clutch bearing by transferring the heat.

torqueaddict on Sun June 29, 2014 1:36 PM

I was monitoring the pressure and I noticed that when the belt slips, the pressure is high (off the charts) and when the belt stops slipping the pressure returns to the normal range.

Is this typical behavior? When I first turn the system on, the pressure is normal and it intermittently gets high.

Thanks hopefully I am closing in on solving the problem!

bohica2xo on Sun June 29, 2014 2:53 PM

Need some more info here.

"Off the charts high" - what would that be in PSI exactly?

Assuming this is an OEM system with a functioning POA & TXV, was the POA adjusted for 134a?

When you say after 15 minutes, is this 15 minutes idling in the driveway?


Put the gauges on it, and open both doors. Set the cabin fan to the highest speed, and start the engine. record the idle pressures. Now run the engine up to 1500+ RPM, and hold it there for a minute. Record the pressures while still holding the 1500 RPM. Post the results.

.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Jag987 on Sun June 29, 2014 3:37 PM

High or low side off the charts high?

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

torqueaddict on Sun June 29, 2014 4:35 PM

torqueaddict on Sun June 29, 2014 4:41 PM

All readings were low side at idle with ac on high - system was converted to 132a.

When the compressor was slipping I noticed the pressure was over 80psi. When the compressor was not slipping it was around 40psi.

I can't do the 1500 rpm test now but hopefully these pressure fluctuations mean something.

I did have a shop get this ac going at a cost of around 800. (not sure all of what they did but they did replace all the rubber hoses) They are hard me for me to get to unfortunately but I think I may have go leave it for them to finish.

torqueaddict on Sun June 29, 2014 4:54 PM

So I just read somewhere that it's normal for it to read that high with ac off and since the belt was slipping that makes sense. Yes I am a noob at this.

thanks for the responses. I am guessing I just need a compressor and it probably seemed ok when the shop gave me the car back.

wptski on Sun June 29, 2014 5:06 PM

Quote
Originally posted by: torqueaddict
So I just read somewhere that it's normal for it to read that high with ac off and since the belt was slipping that makes sense. Yes I am a noob at this.

thanks for the responses. I am guessing I just need a compressor and it probably seemed ok when the shop gave me the car back.
When the compressor isn't turning for whatever reason the low side will go up and the high side will go down. Your first post stated 90F, so if engine and all components were at 90F the pressure on both high and low would be around 103psi. If not you don't have enough liquid refrigerant in the system to create a vapor pressure. If you had much higher than 103psi, you have air in the system.

bohica2xo on Sun June 29, 2014 7:45 PM

Low side testing won't answer the question.

Buy a set of gauges, and post some pics of the system so we can determine what you have.

The compressor is capable of pumping, or it would not load the engine down while cooling.

You could have airflow issues with the condensor, control valve problems or simply an overcharged system. No way to tell without a set of gauges.

Don't worry about being a "noob" here. We can help you through it. Worry more about a shop that handed the vehicle back to you that has issues. Learn to do the A/C work, or at least diagnose the system. It will save you a lot of money & aggravation in the long run. A quality gauge set is 75 bucks from the site sponsor HERE



-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

wptski on Mon June 30, 2014 8:14 AM

That MC gauge setup is with 1/4" flare fittings. The OP is saying R132A, I assume they mean R134A so they'd need adapters or a different set.

bohica2xo on Mon June 30, 2014 10:31 AM

Adapters are available locally - IF he needs them.

It is impossible to say what he needs without seeing what was done to the system. The car came with R12 ports.

It may have a 2 dollar "POA eliminator", be full of HC refrigerant, or bone stock with 3 coats of enamel on the condensor & a dead fan clutch. It sure sounds like it has no HPCO...

The OP needs to post some pics, and look around under the hood for a label telling him exactly what was put in the system. Until then, it is all assumptions like yours.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

torqueaddict on Fri July 04, 2014 10:38 AM

Thanks for all of the info. I did end up taking it back to the shop and they did end up replacing the compressor. The car is done but I have not seen it for myself (long story but my father in law picked up the car for me and he has it) I should have the car back today so I can make sure that all is well. My father in law said it is blowing cold but on max it doesn't get "too cold" like a new car so maybe more tweaks are needed later on.

It was around $400 out the door so at least it wasn't too bad.