Problem with AC on 1990
Thread Starter
Instructor
Joined: Dec 2011
Posts: 146
Likes: 1
From: Kenton Ohio
Problem with AC on 1990
Ok ac was empty so we pump put nitrogen in it to see if there was any leaks. There we're none so we started car to see if pump would kick on to eliminate another problem. It kicked on and killed the motor. So unhooked pump started car looked at gauges to see what was going on it shot up to 400psi and would of killed it again if we didn't unplug it. Lines are all clean we looked at that filter and nothing in it. Question is what would it be? Would it be that high from the nitrogen or the high limit is bad or pump?
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Have never tested with nitrogen. An empty system needs a shot of freon & an electronic leak detector to find the problem.
How high was the static pressure?
70 - 80 lbs should be max with the system off.
Check the compressor to insure it turns smoothly then check the dryer. After removing the dryer disconnect the AC lines at the compressor. you can blow shop air through the system to insure there is not a blockage.
How high was the static pressure?
70 - 80 lbs should be max with the system off.
Check the compressor to insure it turns smoothly then check the dryer. After removing the dryer disconnect the AC lines at the compressor. you can blow shop air through the system to insure there is not a blockage.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Well the good news is that they don't make pressure when they're broken, so the compressor is probably ok, but you might look on the hood to see if it's covered in compressor oil which would indicate that the shaft seal is shot.
Gas doesn't evaporate so there's a either a leak or someone purposely let it all out.
Rapid pressure rise to the high limit means it's completely plugged up. I'd suspect at the Condenser and that may be why you couldn't find a leak. Anyway, that's usually because the Accumulator fell apart and they usually fall apart once you start mixing gasses. I'd start by getting a new Condenser along with an Accumulator and then you're going to need to flush all the lines and the Evaporator and you might as well put in a new orifice. If you don't get all the junk out, it'll just plug back up, though hopefully, with a new Condenser, you'll only have to worry about the outlet to the orifice. You're also going to need to find the leak, so once it's back together, I'd take it to a shop where they can put some gas in it and then sniff around with an Electronic Detector to find the Leak.
Gas doesn't evaporate so there's a either a leak or someone purposely let it all out.
Rapid pressure rise to the high limit means it's completely plugged up. I'd suspect at the Condenser and that may be why you couldn't find a leak. Anyway, that's usually because the Accumulator fell apart and they usually fall apart once you start mixing gasses. I'd start by getting a new Condenser along with an Accumulator and then you're going to need to flush all the lines and the Evaporator and you might as well put in a new orifice. If you don't get all the junk out, it'll just plug back up, though hopefully, with a new Condenser, you'll only have to worry about the outlet to the orifice. You're also going to need to find the leak, so once it's back together, I'd take it to a shop where they can put some gas in it and then sniff around with an Electronic Detector to find the Leak.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
PS - there is a relief valve on the rear head that opens at around 600 psi when the hi limit fails. If you made 400, someone probably made a lot more at some point and that's where the gas went.
Thread Starter
Instructor
Joined: Dec 2011
Posts: 146
Likes: 1
From: Kenton Ohio
Well you use nitrogen if the system is empty because it is alot cheaper than wasting freon and just soap and water on everything works great in finding leaks.
there is no compressor oil on the hood and you can turn the pump freely.
there is no compressor oil on the hood and you can turn the pump freely.
