A/C cold...then cool and humid

[prerunner1982]

The A/C in my "new" 2000 XJ will blow nice and cold for awhile... 5 mins... maybe 20 mins then it will blow just cool air but it's humid air. If I turn it off for awhile and back on it will blow cold again for awhile then cool and humid again.

Sometimes it won't get cold at all...

Not sure if both symptoms are related or not.

Any ideas?

A tech at my work said it could be the electric fan on the radiator not kicking on. I have noticed it doesn't kick on with the A/C but will when the engine temp gets high enough. I have heard it kick on for a min or less and then kick off again, I have heard it do that a couple of times.

[Mudderoy]

The A/C in my "new" 2000 XJ will blow nice and cold for awhile... 5 mins... maybe 20 mins then it will blow just cool air but it's humid air. If I turn it off for awhile and back on it will blow cold again for awhile then cool and humid again.

Sometimes it won't get cold at all...

Not sure if both symptoms are related or not.

Any ideas?

A tech at my work said it could be the electric fan on the radiator not kicking on. I have noticed it doesn't kick on with the A/C but will when the engine temp gets high enough. I have heard it kick on for a min or less and then kick off again, I have heard it do that a couple of times.

Seems like I remember Matt telling me that if that electric fan doesn't come on with the compressor you can have very high head pressures leading to a compressor failure, but don't quote me.

[Pinkyman]

I believe the electric fan should come on anytime that the AC is on. I just replaced mine because it had failed, but my AC still worked, it was just cooler when I was moving.


You may want to look into the AC compressor "shim mod." I had to do this to mine as well. Basically the air gap between the compressor and the compressor clutch gets too large, and the magnet will not engage. This happens after running for a few minutes. You can correct it by pulling the compressor clutch off (you leave the compressor in and even leave the belt on), there will be 3 tiny metal shims on the shaft of the clutch when you pull it out. Remove one of the shims and try it again. It sounds like this may be your issue, and it's like a 10 minute fix.

The hardest part is getting the clutch off. Try not to pry it, but rather pull it straight out by hand if possible.


This guy pulled his belt off, but it's not necessary.

https://youtu.be/V_s8AOqEMgw

[4.3LXJ]

The symptoms you describe are typical of the evaporator core icing up. When you turn it off, it is melting the ice and then works until it ices up again. This is caused by being slightly undercharged.

[prerunner1982]

This last Sunday I removed a shim from the AC compressor clutch and so far that seems to have fixed the issue.

[Pinkyman]

This last Sunday I removed a shim from the AC compressor clutch and so far that seems to have fixed the issue.

Boom! Glad to hear it :thumbsup:

[prerunner1982]

Wish I would have done it sooner, hardest part was trying to hold the clutch from spinning while getting the nut off.