Here's the deal. When I start my XJ the AC clutch will kick on and blow cold just fine. After I drive it for a while the AC will stop cooling, the just blows. If I turn the XJ off and let it sit for a while, then turn it back on the AC will blow cool for just a little while, then stop blowing cool air. I had the refridgerant (spelling sucks) checked and it is fine. Do yall think it could be the AC switch on the high side? Thanks

 

bump. Anyone??

 

Low/High pressures @ what ambient? Are you sure the clutch isn't giving up? Does the compressor stop cycling or does the system freeze solid. You really didn't post much info to go on, i.e. works -/+ doesn't work = could be a million things.

 

I'd start by finding out if the compressor is still running when it stops getting cold - tell us.

Then I'd take a close look by the dryer - look for the expansion valve - it will have a copper tube coming out of it - if it's that type. Follow that tube - it will go through the firewall and in between the fins on the evaporator - cold coils. Make sure it's shoved all the way in and not dangling somewhere out side of it. It cycles the compressor when it senses it's too cold in danger of icing up.

If it's not in the right place it can get too cold and freeze up, then it blows warm - till it sits awhile and melts.
Someone working on it may have pulled it out a little accidentally.

But - if you don't see the thin copper tube, it's the newer kind.

 

The high side pressure switch is there to prevent the compressor from operating in the event of excessive pressure. You mentioned that you had your pressure checked. Did they use manifold gauges to check both low and high side pressures? Excessive high side pressure could mean a clogged orifice valve. The high side pressure switch could be bad and cutting out the compressor at too low of pressure.

It sounds more like your evaporator may be freezing up. X2 on checking if the compressor clutch is engaged when it is blowing warm air. If after sitting for a while is there a large puddle of water underneath? If so it may mean that the evaporator may have had ice clogging the fins which prevents/resticts air flow.

You could try replacing the low pressure switch (at the accumulator) it's easy to replace without any loss of charge. If the switch is defective it may not allow the compressor to cycle (cycling is normal) which will not allow the surface frost to melt and ice will form.

If the compressor is not engaging after runing for a while then (due to high under-hood temp) there may be an excessive gap at the clutch that can be corrected by removing a shim. If that's the case there are a lot of write ups on how to do it.

 

The compressor clutch is not engaged when it is blowing warm air. When I first start the jeep the compressor will engage and blow ice cold air. After driving for a while it will start to blow warm air. I have pulled over and checked under the hood and the compressor clutch is not engaged when this happens.