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Volatile
September 26th, 2017, 08:55
Hi all,

Recently, my blower fan in my 91 Laredo stopped working. I could feel the heat coming from my defroster vents when moving, but then it would stop as soon as I came to a stop. I also noticed the slider to the AC positions doesnít engage anything, neither the AC condenser nor the electric fan.

After finding the blower motor fuse to be fine, I pulled the HVAC panel itself to find this:

https://imgur.com/gallery/Y9Ezq

After googling a bit it seems like this is common, though my harness doesnít seem to be melted, but it is definitely gunked up with this slimy stuff you see in the picture. This is after wiping it off a bit. The prongs on the resistor are in a similar condition.

Iím nowhere near u-pick, can I just order new parts from Rock auto and be good to go? Or can I just clean this up and hook it all back together, since it doesnít look melted?

And a potentially stupid side question: will my e-fan still engage when reaching the designated engine temp? My instinct says yes as Iím assuming the fan gets its signal from the thermostat.

Thanks in advance, I was actually starting to think this thing was done giving me problems for more than a week.:gee:

Heavyopp
September 26th, 2017, 09:04
That slimy stuff is just a dielectric compound used to keep corrosion down -- cleaning it up and reconnecting shouldn't change anything

Anak
September 26th, 2017, 09:22
That doesn't look like your problem.

How does the resistor look down in the passenger footwell? Mine had an obvious break in the wire.

Volatile
September 26th, 2017, 10:18
That doesn't look like your problem.

How does the resistor look down in the passenger footwell? Mine had an obvious break in the wire.

I just checked, and all of my wiring looks to be in great shape. Is there a way to test the resistor itself?

Green XJ Jeep
September 26th, 2017, 11:13
That doesn't look like your problem.

How does the resistor look down in the passenger footwell? Mine had an obvious break in the wire.
I though the fan would still work in high if the resistor blew. Mine did and it was real obvious it blew.

Volatile
September 26th, 2017, 11:23
I though the fan would still work in high if the resistor blew. Mine did and it was real obvious it blew.

Iím also reading that the high setting bypasses the resistor altogether.

I did check for voltage at every wire with the key on, and Iím not getting anything from any of them. Shouldnít I at least be seeing some kind of voltage in one of the switchís positions?

Anak
September 26th, 2017, 15:14
Back up and see if you have power to the switch itself. I think one of those wires should be hot with the ignition on.

Volatile
September 27th, 2017, 08:26
Back up and see if you have power to the switch itself. I think one of those wires should be hot with the ignition on.

I probed each wire coming out of the back of the HVAC panel with the switch in different positions and the ignition on. I didn't get anything. Is this a resistor symptom? I can't seem to find any other replaceable part other than the blower motor itself and the resistor.

Anak
September 27th, 2017, 08:38
A relevant wiring schematic can be found here:

http://www.jeepforum.com/forum/f11/definitive-blower-motor-blown-melted-resistor-switch-wire-fix-580627/

It appears the yellow/ brown wire is the one in that connector which should have power, but it depends on the heat mode selector.

Figure out where you do have power and where you don't. Test at the fuse just to make sure there is power on both sides of it, then work forward in the circuit from there.

Volatile
September 27th, 2017, 12:40
Well I feel like an idiot.

While looking over that schematic and matching up the different wire colors, I discovered that the flat black harness plugged into the back right of the HVAC panel had come loose due to a worn out clip. I re-seated it and everything is back to normal.

Thanks again for all the help!

Anak
September 27th, 2017, 14:43
Happy to Help.