New AC compressor, what do I do about PAG oil?

[Fireball5657]

Hey all, 94 Sierra with a 5.7 and factory R134 AC. It’s had issues with the ac since 2007, the previous owner kinda just gave up on it and I haven’t bothered with it much until last year, when I replaced the compressor, orfice tube, condenser, and the accumulator. The old system was all original and didn’t have any crap like metal flakes or dirt in it, so I know the system is clean. The AC compressor I bought was a reman and ended up being a pos, it locked up the clutch and threw the belt any time you turned the ac on, so I haven’t touched it since then. Now some of my issues also were user error, hence why I’m here. But anyways, it’s 95 degrees in OK and I just warrantied my old compressor and bought a brand new one. But I have a few questions about PAG oil.

Firstly, what kind should it use? I used PAG 150 last time, but i’m not sure if that was the best idea. If it helps, it’s a brand new Murray compressor.

Second, how much should I add? The sticker on the compressor said that it came with 3 oz already in it, but I don’t know if the oil in it is worth a damn or not.

Lastly, how do I get the oil to fill up in the compressor properly? I know to turn the clutch, but how can I do that when the compressor is out of the truck? That was something I didn’t do that last time and I want to do this one right.

Thanks from a GMT400 owning Oklahoman who’s sweating his ass off every day!

 

[kenh]

A quick google search will give you the correct amount of oil for your system. If you want to go that route then a complete flush of the system will remove all traces of oil so you can start from scratch.

I converted my "90" R12 system to 134A so had to flush out the old oil. Started with lacquer thinner and finished with an approved flush. Lacquer thinner to remove the bulk of the oil/contamination and the approved flush to remove the lacquer thinner just to make sure the system was ready. The pump does not turn hard and you don't need to make 100 revs. I just used a ratchet to make the required turns documented in the pump instructions. I dumped the extra oil in the accumulator. I think my system held 8 ounces of oil and type/viscosity was documented in the pump instructions.

Too much oil is just as bad as too little.

Ken

 

[Erik the Awful]

Choctaw, where "4th of July Weekend" means the two weeks before and after the 4th when everyone set off fireworks until midnight.

 

[Dariusz Salomon]

Hey all, 94 Sierra with a 5.7 and factory R134 AC. It’s had issues with the ac since 2007, the previous owner kinda just gave up on it and I haven’t bothered with it much until last year, when I replaced the compressor, orfice tube, condenser, and the accumulator. The old system was all original and didn’t have any crap like metal flakes or dirt in it, so I know the system is clean. The AC compressor I bought was a reman and ended up being a pos, it locked up the clutch and threw the belt any time you turned the ac on, so I haven’t touched it since then. Now some of my issues also were user error, hence why I’m here. But anyways, it’s 95 degrees in OK and I just warrantied my old compressor and bought a brand new one. But I have a few questions about PAG oil.

Firstly, what kind should it use? I used PAG 150 last time, but i’m not sure if that was the best idea. If it helps, it’s a brand new Murray compressor.

Second, how much should I add? The sticker on the compressor said that it came with 3 oz already in it, but I don’t know if the oil in it is worth a damn or not.

Lastly, how do I get the oil to fill up in the compressor properly? I know to turn the clutch, but how can I do that when the compressor is out of the truck? That was something I didn’t do that last time and I want to do this one right.

Thanks from a GMT400 owning Oklahoman who’s sweating his ass off every day!

You turn compressor by hand few times-instruction should give the numbers. Pag150 is good oil-in general that's what we should run in those trucks. Each system has a specific amont of oil/refrigerant. This is the chart I think I used.