2nd Gen Non-Engine/Transmission A/C not cold anymore

[surfbeetle]

So my A/C is now gotten intermittent. I have to turn it on and off with the upper knob in the control panel (not the fan control) and it will usually come back on. Could this be the control unit or is the compressor clutch going out now? I had to change the a/c relay in the black box under the hood a couple of years ago. When the a/c fails to turn on, I can see the compressor is not engaged, how can I check to see if it is the control unit or a bad a/c clutch. Truck is a 95 12valve with 194,000 miles, it's the original a/c system. Thanks in advance, weather is starting to warm up and I'm soon to need my a/c.

 

[madmanmanick]

The way you can check this is by pulling the front bezel off the dash, then remove the control assembly. Use a multimeter and check the voltage of each of the contacts. As you shift the modes of operation take readings. If you shift the mode to A/C and you don't read any volts than the control is bad. Now to check the clutch crawl under the truck and have somebody else turn the A/C on and off. If you do not hear the clutch engage and disengage than the clutch may be bad. There is one exception, if you do not have enough refrigerant charge than the LP switch will not allow the clutch to engage. That can be checked by attaching a manifold or a gauge to the low pressure side of the system. The reading for the system if the charge is right is 32-40 psi. If the pressure is low and is fluctuating up and down the system will be turning on and off intermittently. Hope this helps

 

[surfbeetle]

Thanks alot, that definitely helps. I know what I'll be doing on Saturday.

 

[B.G. Smith]

With the mileage you have on the original system the air gap on the clutch is probably excessive and could be the cause of the intermitten engagement. The gap between the clutch face and disc should be like . 016" to . 031". The gap is adjusted by adding or removing spacer washers from the compressor shaft behind the clutch disc. Some of the discs come off fairly easy, others requiire a special puller. bg

 

[surfbeetle]

With the mileage you have on the original system the air gap on the clutch is probably excessive and could be the cause of the intermitten engagement. The gap between the clutch face and disc should be like . 016" to . 031". The gap is adjusted by adding or removing spacer washers from the compressor shaft behind the clutch disc. Some of the discs come off fairly easy, others requiire a special puller. bg

I thought of this also as my wife's previous suburban had to have the clutch adjusted. The compressor on that one was at the top of the engine, if I tapped the clutch when the engine was running, it would click on.



I am going to start with the controls to ensure that there is power up to the clutch on the compressor. If it turns out that the clutch is bad, then I will take it in to an a/c place that I've been very happy with in the past. I want to make sure I do all that I can before spending money on a diagnosis that I could have done myself.