1998 Monte Carlo a/c compressor

[mark_gober]

Hey everyone,

New to this particular forum, but post often in the Windstar forum. I'm trying to help my father/stepmom get some a/c in her car. She's got a 1998 Monte Carlo with the 3.8l.

I have a vacuum pump and compressor gauges so they brought it to me. It was low on freon so I went ahead and charged it. Not empty, but low. Due to not being empty, I decided not to pull a vacuum. (Probably should have in retrospect.) Anyway, I charged it up and the blowers were blowing cold. Not as cold as I'd have liked, but certainly cold. I believe with an ambient temp of around 90, they were blowing around 72.

I thought I had it licked and decided to drive it to work once before I gave it back. About halfway to work, it just got warm and never did get cold again. When I got to work, I checked the compressor and it's still engaging when you turn the a/c on.

I did some research on these V5 compressors and found a very interesting article regarding the refrigerant control valve on the compressor and how they are very susceptible to failure. The article mentioned that when they go bad, it has symptoms that indicate the compressor is bad, but it's just the RCV. They can be purchased for around $40, but I'm gonna lose the freon to put it in there. A new compressor on Amazon (and one locally) can be purchased for around $155ish. I'm trying to see if anyone's ever had any luck changing out the RCV and if that fixed the problem.

The interesting thing I see now is that even with the compressor engaging/disengaging, I see absolutely no change in my pressures. They are the same whether or not the engine is revving or at idle. Basically I'm seeing the static pressure, because both high and low ports are the same reading. I'm not a pro on the variable displacement compressors, and hopefully someone can give me some insight into them..

Sincerely,

Mark

[brcidd]

Are you sure there is correct amount of refrigerant in system? 2 lbs is spec.

[mark_gober]

Originally Posted by brcidd

Are you sure there is correct amount of refrigerant in system? 2 lbs is spec.

Yes. I put two and 1/2 cans. It already had a little in it, so that should be right around 2 lbs.

The interesting thing is that the compressor is engaging, but the pressures don't change.

Mark

[Blue Bowtie]

That's odd, since my tables show a Monte with a Buick 231 is not supposed to get a variable compressor. I wonder if it was a replacement.

What were the high/low side pressures at the 90 ambient? If not much above 110 PSI and with no differential there may be a complete short-circuit of refrigerant from the pressure control or a bad valves, snapped shaft, etc.

Did you add any PAG with the refrigerant?

[brcidd]

Originally Posted by Blue Bowtie

That's odd, since my tables show a Monte with a Buick 231 is not supposed to get a variable compressor. I wonder if it was a replacement.

You sure you are looking at 1998 MY?-- all W-cars builit in Oshawa got either 3.1L or 3.8L engines- both used V-5 compressors in '98.

[mark_gober]

Originally Posted by Blue Bowtie

That's odd, since my tables show a Monte with a Buick 231 is not supposed to get a variable compressor. I wonder if it was a replacement.

What were the high/low side pressures at the 90 ambient? If not much above 110 PSI and with no differential there may be a complete short-circuit of refrigerant from the pressure control or a bad valves, snapped shaft, etc.

Did you add any PAG with the refrigerant?

I'm not sure what table you're looking at, but it is the correct factory compressor for this car. It matches the compressors shown on various websites like Rockauto and Autozone. The V5 is a variable displacement compressor.

I did not add any PAG to the refrigerant, but it still had positive pressure and so I chose to forgo that.