Replacing the AC Blower Motor Resistor

(April 28, 2008) Apparently, the blower motor resistor on a Cherokee was not designed very well.  Take a look at ads for used Cherokee's and you'll see that most of them say "AC fan only works on high."  (Most of them also say the windshield is cracked, but I'm not going into that here).  This is more an inconvenience than anything else, but for me, it's too noisy with the fan on high and too hot with the AC turned off.

This project turned out to be a lot easier (and cheaper) than I thought it would, although I did have to order the part and wait for it to come in.  The dealer had it the next day though.

The first thing I had to do was to find this resistor.  I really wasn't sure what I was looking for, although I knew it was somewhere under the glove box.

If you get down on your knees and twist your neck around at an unnatural angle, looking up from under the glove box, you'll see something like the picture in figure 1.  There's a single screw (circled in red) that you have to remove then the cover will drop down and you can pull the cover off of the fastener in the back.

Once you get the cover off, you'll see the resistor and a vent actuator (figure 2).  I only point out the actuator, because it's in the way and will have to be removed.

There are two 5/16 nuts on the bottom of the actuator that hold it in place.  They're not real easy to get to, but eventually, they'll come off.  Once the nuts are off, you'll need to remove the air hose from the bottom.  It just pulls off and you'll see the actuator start to move.  You can then lift the actuator off of its mount and replace the air hose.

Next, pull the electrical connection off of the resistor and remove the two 9/32" fasteners that hold it in place.  You can now pull the resistor straight out.

I had really expected to see burnt out resistors on the back of this thing, but I couldn't tell by looking at it that anything was wrong.  I guess I could have run an ohm meter across the terminals to see what they read, but since I don't know what they should have been, reading them now wasn't much help.  Once removed, the resistor looks like figure 3.

Putting the whole thing back together was as easy as taking it apart.  Put the new resistor in and screw it back into place with the two 9/32" fasteners.  Remove the hose from the actuator again and slide the screw posts back into the holes in the bracket and tighten them back on, then replace the electrical connector.

I then turned the AC off, turned the fan to low and started the vehicle for the big test.  There was a slight burning smell at first, but I guess that was just the new component heating up.  I took it through each of the fan settings and it works like new!