92 chevy truck a/c problems

Forgive me if I'm bringing up an old topic, but I did a search and didn't seem to find what I needed to know so here it goes....

My wife has a 92 Chevy C1500 pickup and a few weeks ago her A/C started squeeling. Having heard this sound in the past on one of my old trucks, I knew immideately it was the clutch on the compresser. So we shut off the A/C immediately and continued on. Last week I went to replace the Compresser and the guy at the parts store told me I didn't need a new accumulator/dryer or orafice (sp?) tube, if it was just the clutch that went out. So, I replaced the compresser, put a vacuum on the system for about 45 minutes /-. BTW...I added oil to the compresser before installing it.

Anyway, the system took a charge and blew cold air, but later that week, it started squeeling again, only this time it continued after turning the A/C off. She pulled over to make sure it was nothing else and noticed smoke pouring out of the compresser and metal shavings all over it as well. When she started the truck back up, the noise was gone.

This weekend we took the compresser back, they told us that compresser went out because we didn't change the accumulater/dryer and orafice tube. They went ahead and exchanged the compresser, and we bought a new accumulater/dryer and orafice tube. Again, I oiled the compresser with 2 ounces of oil, as that is how much was in the old/original compresser. I blew all the lines out with an air hose before installing anything to make sure the shavings were all out and everything blew clear. Was that good or bad? The orafice tube had shavings all over and I picked some out of the line with a magnet, so I figured, better safe than sorry.

Anyway, put it all together, drew a vacuum for 30 minutes, added some pressurized oil, about 4-6 ounces worth to make sure the dryer had some and to make sure the system wasn't dry since I blew it out. A retrofit sticker says it takes 8 ounces total. Anyway, then I continued for another 30 minutes on the vacuum to make sure it had a good vacuum. THen I added 1-12oz can of R134a, which seemed to take forever. During that fill the compresser would kick on and off, as I'm told is normal because of the pressure switch. The guage read about 25-40psi the whole time. Well, on the 2nd can the clutch locked and started squeeling and the clutch isn't moving.

Any ideas? Am I doing something wrong or am I getting trash compressers?? I'm not certified, but a very capable do-it-yourselfer. I've changed several compressers out and even preformed a retro on an old honda when the compresser went out. I've never had these problems. What gives here??

Do I have too much oil by chance?? If so, how do I get it out? Wouldn't blowing through with an air hose push oil out? I tried to place a rag around the blow out hose, caught some oil, but hard to tell how much.

Anyway, sorry for being long winded and thanks for any and all advice. I really hate to spend $600 paying a pro, but I'm also tired of this headache! is the condenser plugged? I take it you have no gauge for the high side. I would be very curious to see what the high side reading was on this system.

Do you know if this system has a high pressure cutout switch? Some of these R12 systems did not have them and they should be installed when the system is retrofitted. Also remember that about 20% less R134a is used than R12 when charging a retrofitted system. I don’t think you over charged the system but I suspect you may have a blockage somewhere. This is where a high side gauge reading is necessary.

I’ll also say that my shop only uses new compressors because we have yet to find a reliable source for remanufactured units. I’ve seen reman compressors that were seized right out of the box.

You might want to check the orifice tube again for any debris that might tell you something if it’s clogged again. It can be very, very difficult to clean the system properly after a catastrophic compressor failure which is why a lot of shops recommended replacing the condenser as the guest suggested. Venturi wrote:I take it you have no gauge for the high side. I would be very curious to see what the high side reading was on this system.
Do you know if this system has a high pressure cutout switch? Some of these R12 systems did not have them and they should be installed when the system is retrofitted. Also remember that about 20% less R134a is used than R12 when charging a retrofitted system. I don’t think you over charged the system but I suspect you may have a blockage somewhere. This is where a high side gauge reading is necessary.

I’ll also say that my shop only uses new compressors because we have yet to find a reliable source for remanufactured units. I’ve seen reman compressors that were seized right out of the box.

You might want to check the orifice tube again for any debris that might tell you something if it’s clogged again. It can be very, very difficult to clean the system properly after a catastrophic compressor failure which is why a lot of shops recommended replacing the condenser as the guest suggested.


Well, my high side fitting isn't making good contact or the guage is bad. Tried on 2 cars and got no reading. I went out last night and got a new gauge, so this time I can get a good accurate reading.

I called several places including a GM dealer and everyone told me I shouldn't need to replace the condenser, so this time I didn't. If it goes again, I am changing my source for the compresser and going new. This last one was from the same chain, but a different store and it was packed much better than the last, so hopefully it's at least a different batch if not brand. I flushed the entire system, minus the compresser, accumulator/dryer, and orifice tube, with laquer thinner based on one ac shops recommendation and the GM dealer saying they use brake cleaner, and that the laquer should be good as well. I poured thinner in until I was able to blow only clean thinner out.

I then let it set for about an hour open, after blowing the lines dry, while I went to change the compresser, dryer, and orifice tube. Blew through the lines with air compresser one more time to make sure no thinner pooled up and installed each component. Being as everything was flushed clean or new, I then installed new oil to the compresser and the dryer per instructions with this compresser. And then finished with the remainder of oil via pressurized can into the low side. The whole time hand turning the compresser both ways to move the oil around well. I then put a 45-60 minute vaccuum on the system before calling it a night. If the vaccumm is still holding when I get off work, I'll draw about another 45 minutes or so of vaccuum to be sure it's dry and start my fill. I'll let you know how it goes this time....

Well, I pulled a vaccum last night for about 45 minutes. Let it sit overnight and checked today and it was still holding the vaccum. To ensure it had a good vaccum, I pulled a vaccum for another 60 minutes tonight. THen I hooked up the high and low side gauges and started charging. I am within a few ounces of where the retro fit sticker says it should hold, but I'm getting about 30 psi on the low side and about 25-30 psi on the high side port. This is with truck running and A/C on full. It's been rainy the last few days and the temp was down in the 70's today.

The A/C is blowing cold and the high line is getting hot, while the low side is chilling nicely. Does it sound like I have a problem or is it likely the pressures are just down because it's low on freon still and the temp is down? I know the low should be about 40-45 and the high about 125 depending on temps.

THanks,
Brian What is the high side reading? It can't be 25-30 psi. Are you sure about the high side pressure? I don’t see how you could have basically the same readings on the low and high side if the system is cooling.

Having a failed compressor you should have a screen installed at the suction side of the compressor if it does not already have one. Venturi wrote:Are you sure about the high side pressure? I don’t see how you could have basically the same readings on the low and high side if the system is cooling.


Well, here is what I found this morning. According to the instructions that came with my gauge it says to open both valves, high and low, when checking pressures, but is what it was doing was just bringing the low side pressure over to the high side. I started thinking that had to be the problem because they were too close.

This morning I unhooked the low side guage and just hooked up the high side gauge and tried to take a high side reading, but got no reading at all. I tried the gauge on my same year suburban and got an accurate reading so I know the gauge is good. I have decided my shradder valve is bad on the high side, so I went to the auto parts store and got a new set. I will drain the system, change the valve, and check the orifice tube. If the orifice tube is fine, I will put another vacuum on and recharge, if not, I think I will install a new condenser as my decision at that point will be that the current one is junk.

I'm hoping that everything is good at this point and that the valve is just clogged, but I'm not taking any chances and changing it to be certain.

Judging by touch the system is working and not plugging up because the lines that should be cold are and the ones that should be hot are hot, which tells me stuff is circulating at least somewhat.

Any other suggestions? Thanks...