My XJ hates me.. I don't even know where to start so I'll get straight to the point. When I turn on the fan for the heat/air conditioning.. It rough idles for a few seconds and then dies.
What we've replaced; both O2 sensors, fan clutch, air filter(due to a muddy day), PCM and checked all fuses.
Has anyone ran into this before?

 

Until someone that knows a lot more shows up...Why not check your vacuum lines to make sure they aren't cracked or anything like that. Also, check to make sure there isn't a short or something causing you to stall.

 

Vacuum would cause it to rev. Get a multi meter and check the draw.

 

We will try anything at this point.. If I may add to my question, my husband installed a stereo right before I started having these problems. But whenever I use the iPod connection the stereo will short out but come right back on.. I haven't brought it up to him (stereo is the least of my worries) but could these two separate issues be one in the same? He's an ASC master tech.. And even he is about to blow the Jeep up. :O

 

Ya the heater controls are right there. Check draw when you turn on the blower. Sounds like a major short. He knows how to test draw at the negative side of the battery right?

 

I'm sure he does. Like I said, I just haven't told him of the stereo problem. (didn't want to stress him out anymore than he already is..lol!) thank you! I'll have him check

 

Yea, on my 90 turning on the fan should not cause a vacuum issue, just the vent controls. Just a volt meter might tell the story...is there one on the dash? (a gauge that says battery, or something, 9,10,11,12,ect). It should stay above 12.

Curious slick, why the negative side?

 

No change on voltage..
Here's the long story (more details)
June- went wheeling got into some pretty deep muddy water. XJ dies in the mud. All the way home acting like it's not getting gas, misfiring & over heating.
Cleaned throttle body, replaced all spark plugs, wires, distributor cap.. Runs but hesitates in stop & go.
July-still hesitates/bad gas milage, code reads O2 sensors, replaced both, over heats during incline, replace fan clutch.. No more heat/air conditioning, still hesitates. Code reads short to O2, rewired. (still heat problem)
August- hesitates starting.. Have to prime the fuel pump before it will start. No heat/air conditioning
September- replaced PCM, have heat/air conditioning for 15 minutes, check engine light comes on.. No heat again. Boo! Sat, new breaks. Sun morning; no oil pressure on gauge.. But have oil pressure. New sensor. & the stupid thing over heats. (GAH! Replaced entire cooling system last winter including radiator) I cool it down and have no problem getting it home. But still, the fan will kill the engine.

 

What I was referring to is amp draw not voltage. Disconnect your negative cable and tape one probe to the cable and one to the negative battery post. Set it to amps and make sure the red wire is plugged in to the top hole. Turn key to on don't start and read amp draw. Next turn the fan on amd read draw. I'm sure you checked that the alternator isn't grounding out right? You definitely seem to have something shorting. After you check draw try pulling the stereo and the hvac controls. Get back there with the key on and the fan on and start juggling. These things are funny about shorts. The strangest things will effect other things. I've seen the radio short and make the brake lights go out for instance.