Deadbolt

Checked search with no luck, so here it goes.

My 2001 Jeep Cherokee (4.0L 4x4 automatic, AC, etc) is experiencing a new environment with the Utah heat; used to live in Seattle.

Well, the other day, the blower did not work. Got in the vehicle after work and when I tried to crank up the AC... nothing. No blower, no AC, nothing. Tried different settings to see if it was the switch. Still nothing. Intended to diagnose when I got home, so thankfully, I had 4-60 AC (4 windows down, 60mph).

Suddenly, the blower started working when I was sitting in traffic. The AC came on and everything acted as though there wasn't a problem. Figured it might be a short somewhere, but didn't have time to look too deep.

Well, it has been working just fine, but there are some weird issues that my factory service manual just doesn't seem to cover. For instance:

1. When I turn on the AC, the blower works for a few seconds, and then momentarily shuts off. Then it comes back on again and blows cold air.

2. Occasionally, when switching from AC vent to AC floor/vent and AC recirculate, the blower will stop working for a couple of seconds and then start up again.

3. Just today, the blower didn't want to work at all, even after cycling through the AC and ventilation positions. It came on after a minute of playing with the controls, and for some reason, it wanted to turn off when I set it to speed 4. After shutting off momentarily, it came back on and ran fine again.

This is obviously an intermittent issue that has me concerned. With expected highs in the 90's and over 100 degrees forecast for the next few weeks, I really don't want to be sitting in SLC traffic with no AC. Somebody surely has had this issue before, or perhaps it's something common?

One last thing, I don't know if it was my Jeep or where I was driving, but for a minute or so, I smelled what seemed to be electrical coming from the vent. Don't know if that motor is on the fritz or what. I'm going to crack it open this weekend to poke around, but if anybody has experienced this before, I would be grateful for any insight you might have.

Many thanks!

cmartin2112

I have never had this issue before... But I can tell you it sounds like a electrical short is in the making. You can try looking around under the dash and seeing if there is anything weird going on. Check all your fuses too.

Radi

Under the dash on the passenger side you should find the resistor box + plug. That plug sometimes overheats and goes intermittent or melts entirely. I'd look at that assembly for problems.

Enginebuilder

Visually inspect the circuit wiring from the HVAC control module to the resistor pack, to the blower motor. (some disassembly of the dashboard required) Pay close attention to the harness connectors, looking for discolored, broken or melted connectors.

If a visual inspection does not show any outward signs of issues, it is time to break out the DVOM (Digital Volt-Ohm Meter) and get to checking for voltage drop. The blower motor should get nearly battery voltage (13.5-14vdc with engine started, ~12v with engine off) with the blower control set on it's highest setting. The other settings on the blower control run through a resistor pack, and will therefore be less than battery voltage.

If there does not seem to be any problems with the wiring, replace the A/C relay.

freegdr

what they said ^^^^ also ceck all fuses for looseness in fuse box

prcjeep

Did you find the culprit for this?? I have a 96 and have been having the same issues for about 3 months. Finnally it stopped all together and i pulled the dash bezel got it to work and saw that it was melting and smoldering in both connectors to the back of the hac switch unit... both the plugs and some of the blades are toast so no AC for me until I hit up the junk yard

freegdr

Melted at the fan switch?

prcjeep

Yup... both sides were smoking when I had the bezel of and got it running. The plugs' outside moldings were discolored and melted or still melting.
Right now its hanging half way out of the dash still attached by the dampener cable

Deadbolt

It turned out to be the blower motor after all. We've been having a lot of 95 degree + days here in Utah, and the motor would not work in the afternoons, when the underhood temps soar above 210 degrees, and the ambient air temp is 100+ on the concrete. But it was working in the mornings. Either the terminals, or the windings were breaking contact in the motor, which I verified with my DMM. In the cool of the evening, I measured 50+ ohms across the terminals, which is too much by itself, but in the afternoon, just after work, I measured it again, but had no continuity.

Pulled it out and got a new one. For kicks and grins, I ohmed the new one out and got about 6 ohms.

The new motor blew harder than the old one ever did, but the inferior plastic made for a bit of a problem because even though I took great care in installing it, something might have cracked or the materials were inferior (chinese made after all), and the new blower grenaded on me today. Fortunately, Autozone will exchange it. I'm glad they will because this is the closest I've ever gotten to wiping my butt with a one-hundred dollar bill.

Deadbolt

You know, just to be on the safe side, I might pull the dash panel and look at the wiring behind my switches.

prcjeep

Ill see if I have any pictures of them to post up...This issue is going to be my weekend XJ fix

Deadbolt

I know why the first motor grenaded on me. After getting the replacement motor at autozone, I opened it up to look at it. I noticed that there were two small metal tabs on the wheel. When I asked the guy what they were, he said they are balancing weights. Hmm. My first replacement motor didn't have any. These motors rotate fast enough that if they were off balance by as little as an ounce, they'd shake apart, as it seems was the case here. Anyway, got the new motor installed and it seems to be working great. Here's to hoping this one doesn't explode when I need it most.

tgordon

I had to replace the blower on my 90 XJ recently. Bought mine at O'Reilly, and came without a new fan. Fan was a pain to remove from old blower.
Damaged the center flange of the fan and had to do some "creative engineering" before I got it all back together.
I also noticed more fan/blower speed with the new one.
BTW, I live downtown SLC, know what you mean by the traffic comment.

Deadbolt

Yup, Sitting right there off State and 7200 S. I'm going to submit to the UT legislature that they change the state bird to the orange barrels that UDOT loves to place everywhere on every street.