PDA

View Full Version : A/c clutch not kicking in/ instument temp not working


Dads XJ
September 6th, 2010, 09:29
The electric fan wasn't kicking on. I thought it was bad but it runs when I uplug the wire from the temp housing. I've switched relays for the a/c with ones that I know work. All fuses in the PDC are good. When I put a jumper from the battery to the a/c wice the clutch clicks like it works, have'nt done this when it's running though. Am I missing a relay under the dash inside. Is there a low 134a level switch somewhere keeping it from cycling on. The sight glass looks like it's full on the receiver-drier. As for the temp, the sender is new ,fuses under dash are all good. Would the gauge needle in the panel be shot? All on a 1996 XJ,4.0, 4x4,auto. Power windows and door locks only, not sure if it matters but what the :flame: thought I would let you know.

Pelican
September 6th, 2010, 09:50
Forgetting everything else for a moment, what is the history of the a/c not working.

Did you get the sender for the gauge as opposed to the sender for the idiot light?

Does the Efan ever come on (other than when you unplug the wire from the sensor in the tstat housing)?

Dads XJ
September 6th, 2010, 11:39
As for a/c history,not sure, bought jeep w/ a blown motor. It did sit for a year before my son bought it.

As for the sender, It's the one on the left rear head. Told the guy at the counter need temp to gauge sender. When I upgraded my instument cluster I don't remember changing mine out and the gauge needle worked, I could be wrong. My wife said I have a short memory. Is there a diff? Sorry if that sounds stupid. I'll go out and switch mine into his and see if it works.

The efan has not come on. Not in defrost. a/c mode, or running. We did put in a 3core radiator

WebDog
September 6th, 2010, 11:47
The AC Compressor will not turn on unless the system pressure is correct, once you get the 134a to correct pressure then it should kick on.

Dads XJ
September 6th, 2010, 12:48
Temp gauge issue solved. Thank you Pelican.

Can I jumper the A/C compressor from the battery while the jeep is running, or will I fry something?

CharlesS
September 6th, 2010, 13:42
There is a pressure switch screwed into the drier/accumulator that is a safety feature for the compressor. If the system is low on refrigerant it stops the compressors clutch from engaging.
You can test the pressure switch by measuring continuity across the terminals. If there is not continuity; then the system is low on refrigerant.
You should take the Jeep to someone that has a refrigerant gauge manifold to see how much; if any pressure remains in the system.
If the system is low on refrigerant; you can inspect the hoses and tubing for signs of dampness caused by oil leakage.

Unless you are familiar with repairing and servicing an air conditioning system I would recommend having system serviced by a qualified technician.

Dads XJ
September 6th, 2010, 17:21
Jumpered the compressor while the jeep was running, made a hell of a racket. Is the compressor shot or would low refrigerant cause it to growl.

CharlesS
September 6th, 2010, 17:32
A lack of oil or bad bearings could cause this. You need to check the system pressure with the compressor off.
Should be around 80 psi depending upon charge and ambient air temperature.