Having trouble getting the cooling fan to work on my Cherokee, its a Classic not Grand. With the A/C on it should run all the time. I pulled the relay out of the power distribution box and checked for power at the #2 terminal of the relay. No power from that terminal. From what I have found there is a fan diode assembly that needs replaced in order for the fan to work. The problem is cannot find anyone that sells a diode assy, nor can I can I find anything that resembles such a part in the engine compartment. Any thoughts?

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With the A/C on it should run all the time

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That I don't believe is true. The newer styles used a pressure transducer to operate the fan on a/c. The xj may be different. You do have 2 fans....If the a/c does not work the other fan wont run.

From what I found looking online which was a print from a Chiltons or one of the repair manuals is that the fan should be running whenever the A/C is on. Otherwise it operates based on engine operating temp. On mine there is only one aux electric fan. The A/C works fine after a full recharge.

Fuse in the PDC (underhood fuse box) is good?

When my 99 xj was new it flickered the headlights when the fan kicked on.
Fix was to add some type of elec box to the fan wiring near the fan and mounted to the inner fender near left headlight.
Then fan ramped on and no more flicker.

Gary.

Yep, the fuse is good.

Wiring diagram shows load side power from PDC and control side power is from 15 amp fuse in the JB (inside fuse box) grounded by PCM.

Gary.

I did a few at work.They were buried in IIRC the pass side and you had to pull a bunch of stuff to get to it.Seems Ma had a problem with them.It should be behind the grill etc.Google it and you should find the location.Rocky

hemi,

I checked the owners manual fuse chart and no mention of a fuse that would control the fan. Maybe its bundled with some other controls?? What you mentioned is that for a 2000 model?

rocks,
From what I found in my research is that the Grand Cherokee has a relay behind the pass side headlight and there is a lot of stuff to remove to get access to it but in my Classic there is nothing that I have found that involves the cooling fan.

2000 XJ.
Control power is ignition switched thru fuse #10 in JB. It also supplies power to control circuits on A/C clutch relay and o2 relays.

With key on there should be B+ on two of the relay pins for the rad. fan relay.

Gary.

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The A/C works fine after a full recharge.

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So the electric fan wont work unless you fix the a/c. The mechanical fan will do the job with no a/c. The electric fan is just a booster for higher temps with the a/c on.

hemi,

Thanks for the help, I will pull the fuse and see what it looks like. I assume that it is possible to have a fuse that "looks" intact but does not work.

The A/C is working now, it blows somewhat cold but not what it should be. Things are starting to warm up here in the desert. I thought the aux fan helps keep the pressure in the A/C system from getting too high. The engine operating temp never gets above 210.

the aux fan only supplements the main fan. when the a/c is on, the condenser makes heat, and a lot of it. the extra fan only helps to cool the radiator and condenser. if your a/c isnt cold, you have a leak somewhere. get it checked, or if you've done the r-134 conversion, add some dye to it, and check it yourself. the kit for checking comes with dye and a u.v. light. cost is like 30 bucks, and worth it if you don't mind doing it yourself.

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I thought the aux fan helps keep the pressure in the A/C system from getting too high.

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It does when the pressure is to high which only can get to high when fully charged and working correctly. The pcm activates the fan relay. The pcm sees several things. A switch command, an a/c high pressure signal. When the pcm sees a high pressure signal it activates the relay which in turn activates the fan.