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68c10airstream · 07-13-2015, 11:26 PM

Welcome aboard, refrigerant fill amount on the underhood panel on top of the radiator.

Gm A/C systems usually hold about 10 ounces of oil for the whole system, with the compressor holding about half of it, as a general rule

Once the old compressor is removed, tilt it back to drain what ever amount of oil is in the compressor, and measure it. If there is almost no oil in the old compressor, i would add 7 ounces, 6 of those ounces into the discharge line at the manifold at the compressor, 1 ounce into the suction side at the manifold, and grab the compressor once it's bolted on and turn it by hand many times to distribute the oil within the compressor.

Are you going to r-134? If so match the oil accordingly!

Did the old compressor lock up?

Just a few facts about the gm ac system, In a properly working system oil is constantly moving throughout the system. The accumulator (receiver drier) mounted on the ac box and is about 4" round and the output hose goes directly to the compressor supplies a oil mist by means of a built in dip tube with a very small hole in it to prevent gulping excessive oil into the compressor and busting the compressor from hydraulic lock.

Each component acts a sump because oil will settle out inside of it after shutdown, and then on start up it will start moving again, so when you run low on oil charge and there isn't enough oil to reach the accumulator, the compressor suffers.

When i did my repairs and replaced compressors i took the old accumulator and cut it in half and looked inside for how much oil was inside and if it was dirty or not inside and base my repairs accordingly

Who is doing the repairs? System should be put under a vacuum to remove air and moisture for it to reach peak performance.

A little too much oil is better than too little. Too much oil raises system pressures, and performance is down a bit, too little oil ruins compressor.

Orifice tube should be replaced and matched to the refrigerant to be installed. The orifice tube has a filter screen built into it and compressor pieces always find it. If the old compressor pumped debris into the system before replacement you will probably be replacing the condenser, and if you are moving up to r-134 you should go to the matching serpentine style condenser anyway. Good luck, Brian F.

07-13-2015, 11:26 PM	#2
68c10airstream Registered User Join Date: Mar 2013 Location: Marquette michigan Posts: 828	Re: Changing AC compressor what is the capacity for oil and refrigerant Welcome aboard, refrigerant fill amount on the underhood panel on top of the radiator. Gm A/C systems usually hold about 10 ounces of oil for the whole system, with the compressor holding about half of it, as a general rule Once the old compressor is removed, tilt it back to drain what ever amount of oil is in the compressor, and measure it. If there is almost no oil in the old compressor, i would add 7 ounces, 6 of those ounces into the discharge line at the manifold at the compressor, 1 ounce into the suction side at the manifold, and grab the compressor once it's bolted on and turn it by hand many times to distribute the oil within the compressor. Are you going to r-134? If so match the oil accordingly! Did the old compressor lock up? Just a few facts about the gm ac system, In a properly working system oil is constantly moving throughout the system. The accumulator (receiver drier) mounted on the ac box and is about 4" round and the output hose goes directly to the compressor supplies a oil mist by means of a built in dip tube with a very small hole in it to prevent gulping excessive oil into the compressor and busting the compressor from hydraulic lock. Each component acts a sump because oil will settle out inside of it after shutdown, and then on start up it will start moving again, so when you run low on oil charge and there isn't enough oil to reach the accumulator, the compressor suffers. When i did my repairs and replaced compressors i took the old accumulator and cut it in half and looked inside for how much oil was inside and if it was dirty or not inside and base my repairs accordingly Who is doing the repairs? System should be put under a vacuum to remove air and moisture for it to reach peak performance. A little too much oil is better than too little. Too much oil raises system pressures, and performance is down a bit, too little oil ruins compressor. Orifice tube should be replaced and matched to the refrigerant to be installed. The orifice tube has a filter screen built into it and compressor pieces always find it. If the old compressor pumped debris into the system before replacement you will probably be replacing the condenser, and if you are moving up to r-134 you should go to the matching serpentine style condenser anyway. Good luck, Brian F.