I had a problem with my heat/vent fan in my TJ. I could only get the high speed to work. I've researched on the situation and the switch could melt at the dash. But this would make all the positions not work. Since I only had high, next check was the relay. Only way to check was to replace. Carquest didn't have one at the Lenexa distro location and would have to order it in at $57. I went to Advance and they still had to order it (3 days), but cost was $36.
Today was a good day to work on it at sunny 56*. The relay is located in the lower plenum area in the passenger footwell. There is a black cover that has to be removed. There are 4 bolts that secure the cover to the black plenum. The upper 2 bolts are holders whereas the bottom 2 are through screws. Once the cover is removed (screw heads are 9mm socket), 2 screws hold the relay into the plenum. Why in? See the pics, it is a Jeep design.
Pull the electrical connector, swap in new one, reconnect connector, check to see if fan works, replace cover back on. Done. It wasn't no more than 15 minutes to get the job done with the pics.
Think there is a problem with the relay?
Comparing new to old.
Open plenum. You can see the 2 upper hold bolts.