SO what was it??? I may have the same issue.

I remember the blower was making noise like it needs to be replaced... could I have melted wires by waiting till the fuse keeps blowing... getting a motor today!!!

 

It might be a good (and cheap) idea to replace the blower motor relay too. I had to replace mine for similar reasons. It was right behind the glove box on my '99 XL.

 

Ok, finaly found the thread I was looking for!

After mucking around with the resistor pack, motor, switch panel, fuse block, and testing and testing and testing.... I called a local auto electric shop and they said check the wiring behind the switch...

It looked ok, but it got me to thinking, and I tested the circuit with a meter between ground and the fuse pin to the blower, then ran the switch through its positions.

What I found was that only ONE position shorted out, with or without the motor plugged in, with or without the resistor pack plugged in.

I happened to have a spare jeep laying around with the dash torn out (don't ask), and was able to retrieve the cable for inspection. The cable between the resistor pack and the speed switch is a straight through cable, with nothing between the two ends as I'd been thinking there might be.

In my case, it appears they pinched this cable during assembly or when someone else poked around, and over time it finally shorted one of the wires to the frame.

I didn't want to tear the dash out (done that once, don't want to do it again), and didn't have time to run another wire, so what I did was clip the shorted wire at both ends (leaving enough on each end in case I want to splice a new one in later), and covered the cut ends (switch side and resistor side) to keep them from touching something else and causing more trouble.

Tested everything again to be sure I got it before putting it all back together

Put it all back together and put in a fresh 25 amp fuse, and how my jeep gets toasty warm. I just lost the second speed as a result. Fortunatly, they way the switch and resistor is set up, the first two positions are now low, with medium and high as the two last positions. Works for me.

So, if you're doing all these other things, replacing motors and resistors and it still blows fuses, don't rule out the possiblity of a frame short in the wiring harness. Isolate the short and fix it the best way you know how.

(BTW, my next "last resort" was going to be grabbing an extra connector and switch and hard wiring the blower for on/off, as it just wasnt cutting it in the cold we were having. This is an option, though extreme, but make sure to put a 25 amp fuse inline if you do this, and grab a tap off of a post-ignition line so you don't forget to turn it off and drain your battery dead after turning off your XJ)

 

right fuse amps

 

Great thread guys.I am about to replace my blower motor too because it is going out.I have one problem that I haven't heard anyone talk about.My heater only works on high so I am guessing that's the switch.Any tips before I do this project?

 

Awesome! I'm so glad you found the short. I've been having similar issues with my blower motor. If it still shorts after the new one is in I'll check this first. I've been waiting to have a good chance to completely rewire under the dash. Lots of old wiring I want to rip out.

 

switch or blower motor resistor

 

HELP HELP!! This is driving me nuts. I just replaced the fried heater resistor with a new one but now it keep blowing the blower motor fuse as soon as I connect it. Any ideas??

 

This just started happening to me, heather blower motor fuse just went I put a new one didnt last a day.

 

Glad I saw this as well. I tested a "new" (read as used to me) A/C & Heat switch for the dash and still got the same results - actually now I'm hearing hissing from the back of the switch. Havent had time to go back to the original and without the time to tear down my dash, I went ahead and ran a new switch to my dash for the blower motor. While this works, it still is not 100% working properly.

So before you go and hot wire a fresh switch or swap out the original switch - check your grounds and wires!

 

Ok so I bought a new blower motor and resistor and instead of blowing a fuse right away it might last two minutes then it blows a fuse? Any ideas?

 

Maybe trace the circuit?

 

Okay found the problem and I feel like punching myself but this might help others in case this has happened to you. So I took off the climate control and my plug wise fried, so I fixed that and the fuse still kept blowing. This was kinda getting frustrating trying to figure this out for a couple hours, so I popped in another fuse and it last longer ???? as I was just sitting there waiting, I started hearing my compressor go on and off like 5 times then POP goes another fuse. Problem was the compressor plug was grounding out against it and my battery. Put some wire loom and tapped it all up and WALA FIXED!

Hope this helps some headaches out there, still kept the new fan and resistor.

 

I have a 90 cherokee that keeps blowing ac blower motor fuse. I've replace blower motor, resister, and ac relay. I need help with what to look at next...

 

Read post #28. Could be the blower speed switch.


Where's the AC Relay in a 1990 XJ?