Hello everyone,
I just bought this Cherokee that I have been chasing down all the little problems it has. So far everything has been pretty straight forward, but I am having an issue with the AC. When I try to turn it on, I get nothing, no compressor engage or blower activation... nada.

I checked fuse number 25 (blower motor relay) on the kick panel: good

Then I tested the blower motor relay (its 4 pin) and its also good. One thing to note is that the relay is being activated (audible click), as soon as I turn the key to power up the car, whether or not the AC switch is on. This seems odd, I would have thought the blower relay coil would only be activated when the AC gets turned to on. With the multimeter negative probe on the negating battery terminal and the ignition key on the "on" position, by probing the relay connector I get 12v on the coil positive, 0V on the coil negative, but then I get 12V positive on BOTH of the remaining connector pins (!?!). Its like if the blower motor was getting 12V from ground and sending it back to the relay?

Another thing I noticed, when I pulled the (aftermarket radio), is that behind the radio there is a white plug that is disconnected, but I couldn't find a plug for it anywhere. Anyone have any idea what this plug is for?

I'm gonna undo the bird's nest that the person that installed the radio made and see if somehow that is related.

In the meanwhile, if anyone has any input, I would REALLY appreciate it.

Thanks!
Frank

 

Blower motor operates at all times the ignition is turned to "ON", what year is this mystery Cherokee? Is it U.S. spec or sumthin else?

 

Lol, sorry:

Its a 1998 Sport and as far as I know its U.S. specs.

I just checked all the fuses in the engine comparment and the passengers kick panel, and they all look good.

I'm gonna start on the stereo wiring mess to see if maybe something is messed up there. I'm still a little curious about that orphan plug behind the radio.

Frank

 

Here is a picture of the orphan connector I found behind the radio. I can't seem to find a plug for it... Anyone know what it is? It only has three wires connected to it blue red and black.

 

Have you checked the freon charge??

 

What year cherokee?

Here us an article that was given to me by CCKen today it has alot of good info in it.

http://www.askamechanic.info/askamech2/content/view/73/47/

You can also unplug and jump out your low pressure sensor and see if your compressor runs as it should.