A/C compressor not working

MLSIGNER

MEMBER
1994 OLDSMOBILE CIERA
3.3L
6 CYL
2WD
AUTOMATIC
224,000 MILES

The compressor will not come on. I have 40-lbs of pressure on both sides of the system. I checked the connector on the compressor and they are attached. I turned the clutch by hand and it is not locked up.
I checked the fuse in the cabin and it is good. Does the compressor need more pressure to come on? Other ideas?

3 Replies

AL514

MECHANIC
4,632 POSTS

Hello thanks for using 2CarPros. If you have a gauge hooked up to the A/C pressure lines, 40 psi is way too low. The low side should be around 30-40 psi and high side around 150-200 psi. The system has a leak and lost all of its refrigerant.

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Saturday, October 12th, 2019 AT 9:31 AM

MLSIGNER

MEMBER
2 POSTS

Well, I finally got the compressor to come on and when I added just a little Freon (probably a few ounces) the low side went up and never came back down to normal operating pressures(went to 80 psi). The high side, after the compressor came on, was running about 190 psi. While running, before I added any Freon, the gauges read 55 psi low side and the high side would go from 100 to 190 psi and then back down. The compressor never cycled off at any point. When I turned everything off, the pressure on the high side came down to about 60 and the high side stayed at 80 psi. Temperature outside is about 60-65 degrees F here. I think it either has a blockage or the compressor is shot. Opinion?

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Saturday, October 12th, 2019 AT 1:24 PM

AL514

MECHANIC
4,632 POSTS

Well at 70 degrees the Low side pressure should be 35-40 psi and high side pressure 145-160 psi. The problem with adding Freon with those kits you can get is that there is no way to know exactly how much Freon is in the system. The proper procedure is to use an A/C recovery machine, remove all the Freon from the system, vacuum the system to make sure all the air and Freon is emptied out completely and make sure the system will hold a vacuum. This will tell you if there are any leaks. Then refill the system with the exact amount of Freon that the manufacturer recommends. If there is a blockage the line pressures will read high. By just adding Freon as you have, there's no way to tell if the readings you're getting are correct or not. The A/C system doesn't take much Freon to operate properly. Around 28 ounces I believe for that system.

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Saturday, October 12th, 2019 AT 3:56 PM