Nate0918

Looks like the clutch failed on my AC compressor and was hoping for some advice on the amount of oil needed to put in/remove. I bought a new compressor that came with 3oz of oil in it, but when I pulled the old compressor, it didn't have any oil in it at all. I assume that the oil is sitting in the rest of the system? If thats the case, should I dump out the oil in the new compressor so I don't add too much to the system? I do have rear AC in the burb, the chart that came with the compressor tells me that my 2003 suburban needs 11oz of oil total. I am replacing the accumulator at the same time. Any advice would be greatly appreciated!

repairman54

NO The new compressor has that oil in it for a reason. Any time an A/C component is replaced it should have a specific amount of oil in it.
The oil settles out in the different parts as it circulates through so leave the oil in it. Total oil amount is there if the system is fully flushed out due to contamination.

Cusser

Myself - I would keep that new oil in there. Since the compressor clutch went out, and the old compressor was NOT seized, you can likely get away with just replacing the compressor and accumulator.

If the old compressor is seized, then I'd also get a new condenser and reverse flush out any high pressure lines, and check the orifice tube itself for debris.

OK to add UV dye with the R134a if the existing system didn't have any dye. But NEVER, NEVER, NEVER add sealer or refrigerant containing a sealer !!!

Nate0918

Gotcha, thanks! No, the old compressor was not seized. I did not see anything obvious in the compressor, tubes, or accumulator. What oil I could see did not have any signs of looking burnt. A common theme I noticed on videos was to measure the amount of oil in the old compressor and put that much in the new compressor. Since there isn't any kind of reservoir in the system I wondered whether the extra three ounces would be too much since its 27% of the total capacity, but I am not a dedicated auto AC tech. I will get the new compressor in and wait for the accumulator to arrive at the parts store!

Cusser

I've found few old compressors to contain a significant amount of oil.

I would've said that if you had left the bad compressor on the vehicle - assuming it still contained R134a - until the new compressor was bolted on, then you likely could've omitted the new accumulator.

When we had a 2005 Yukon 6.0 liter which kept breaking belts due to "compressor slugging" but worked well until the belts broke, I gambled and replaced the compressor only, and added an electronic deslugging device. When we sold the 2005 three years later and got a 2011, I transferred the deslugging device to the 2011. The deslugger is not for fixing a bad compressor, but for preventing damage to a compressor BEFORE it starts slugging. Some models of GM are known for such slugging due to the compressor being low on the engine, and in Arizona and almost 200K miles then, AC was used pretty much full time.

Nate0918

A new accumulator was part of the deal for keeping the warranty on the compressor so I went for it just in case. As for the slugging, I was aware of this in my past HVAC days in regards to liquid refrigerant through a piston style compressor when it didn't all get evaporated, but not oil. Is the slugging due to the oil or the refrigerant? I would assume the oil? I'm ignorant if the process is different in an automotive AC system.

Cusser

I had never heard of "slugging" until I was researching why our 2005 AC seemed to be working fine, but sometimes Mrs. Cusser would hear a noise she could not describe, and not too long afterwards the small AC belt would break. Investigations linked this to oil accumulating in the compressor due to its low location where mounted on the engine. Four Seasons Deslugger was awarded MVAC product of the year, bought mine through Rock Auto and it plugged right in. #36141 https://www.4s.com/en/marketing/the-deslugger