So I was given a 92 gmc sierra 1500 with a 4.3l. I've recently been trying to get the a/c going but have been having hell. 

When I first did anything with it, I just recharged it and got the compressor to spin but it wasn't blowing anything. So I suspected either the orifice tube was clogged or the compressor was junk. I ended up having to buy another line and condenser because the threads on the orifice tube line were galled and stripped. 

After I did that, I recharged the system and added about 1.5oz of oil to the system, and it was working beautifully until the compressor suddenly started grinding really bad, and it stopped blowing cold. I figured it gave up the ghost. 

I then ordered a new compressor, new condenser, and a new filter-drier. I flushed the crap out of the evaporater core, and the lines. I then added 5oz of oil to the system (compressor came with 3oz already), spun the new compressor ten times, put a vacuum to it for an hour, and slowly put two cans of refrigerant in. Worked beautifully again, but then the compressor wouldn't shut off. Then it started grinding. Then something popped really loud like a prv. 

I haven't touched the truck since, because I'm not sure if I fried the new compressor or not. 

Idk what I've done wrong this time. I did everything I could think of, including using almost all new components. And when I say I flushed the evaporater core, I mean I flushed it. I used a/c system flush, and when I ran out, used 95% alcohol to flush it. Then pushed compressed air through it until nothing came out. 

I did pour the oil into the hotside via the suction manifold off the back of the compressor. Then spun it to make sure it didn't pool up (if that's a thing?) 

Idk if anyone is an a/c tech on here, or has links to some good guides. I'm a diyer, so I have my own vacuum pump and a/c manifold, along with a flush gun, and other tools. But I'm shaky at best when it comes to a/c stuff. Thanks for any help/tips/admonishments

What were the high and low pressure readings when the failure occurred the first time?  the second time?  What was the ambient temperature for each time?

 

I am assuming there is an engine clutch fan.  Was it turning?

 

From information you have posted, it seems like the system pressure is excessive on the high side.

 

- John

8 hours ago, Tractorman said:

What were the high and low pressure readings when the failure occurred the first time?  the second time?  What was the ambient temperature for each time?

 

I am assuming there is an engine clutch fan.  Was it turning?

 

From information you have posted, it seems like the system pressure is excessive on the high side.

 

- John

Not sure, I didn't have the manifold hooked up to it because the fittings were kinda janky on the manifold. I ended up using a "gauge" off of one of the parts store cans.

So is it safe to assume the new compressor is junk? Or can it be saved? 

33 minutes ago, Ravewolf said:

So is it safe to assume the new compressor is junk?

 

I would not assume anything.  Did you inspect the first compressor that was suspect for failure?  Was there any metal debris present at the outlet port?  It would probably be best to remove and inspect this compressor for damage before deciding your next step.

 

Earlier I asked if the engine cooling fan was turning (assuming it is an engine fan that pulls air across the condenser).  This answer is important.  If there is no air flowing across the condenser, then compressor output pressure can rise rapidly to a destructive level and will / may activate the the pressure relief valve.  Without gauges (especially a high pressure gauge) you are only guessing at what is going on in the system when the compressor is running.

 

I would definitely install quality gauges on both the low and high pressure ports before doing any further testing.

 

- John

 

 

 

 

 

 

 

21 minutes ago, Tractorman said:

 

I would not assume anything.  Did you inspect the first compressor that was suspect for failure?  Was there any metal debris present at the outlet port?  It would probably be best to remove and inspect this compressor for damage before deciding your next step.

 

Earlier I asked if the engine cooling fan was turning (assuming it is an engine fan that pulls air across the condenser).  This answer is important.  If there is no air flowing across the condenser, then compressor output pressure can rise rapidly to a destructive level and will / may activate the the pressure relief valve.  Without gauges (especially a high pressure gauge) you are only guessing at what is going on in the system when the compressor is running.

 

I would definitely install quality gauges on both the low and high pressure ports before doing any further testing.

 

- John

 

 

 

 

 

 

 

I didn't check but I will next time I have time off. And the gauges are ok, it's the r12 to r34 fitting adapters that are the problem. I'll replace them when I mess with it again. 

Update : 

New compressor shelled itself pretty bad. I think adding the oil the way I did caused it to fail as I added it before the orifice tube, and I'm pretty sure it packed up the filter. I pulled the orifice tube out and it had metal shavings in it. 

My question is, can I add the oil on the low side port before the filter/drier? I found a tool on Amazon that hooks there and let's you inject the oil directly without having to open the system up. It's gonna be a winter thing since I'm broke right now, and I'm replacing everything except for the lines. Also just toying with the idea of putting it together, putting a vacuum on it, then just letting a shop with a machine do it since it's automatic. I'm not the brightest when it comes to a/c work. 

All compressor jobs I've ever done always has the sticker over the hole that you add the oil to. On the 2nd Gen Dodges both 12V and 24V the oil is added in the side of the body. There is a plug in the side of the body and this places the oil in the right place. Never add oil in the lines always add the oil to the compressor in the side port. So the compressor has to be evacuated and pull the compressor and lay it on its side to fill the oil in the body of the compressor.  Then the plug was replaced and snugged up. Now you can install the compressor.

 

If there was trash or as we call it Black Death in the high-pressure side. The entire system requires a flush of all the debris. Most compressor rebuilders require a whole host of parts to be replaced as well.

 

The condenser is going to be full of metal and debris.

Orfice tube / Expansion Valve should be replaced because the filter or the valve will be plugged up with debris.

There are filters inside the accumulator that should be replaced too because of debris settling in the bottom.

Then all lines of the system are blown out with an expensive A/C line flush. Secret you can use Lacquer Thinner too but I will admit either way you will need to change the oil in your vacuum pump in any case. When you pull a vacuum the solvents will turn gaseous and come out into the oil of your vacuum pump. Contaminate your vacuum pump oil.