So my 85 cherokee with the 2.5l heater randomly went whack on me. when i bought it everything worked just fine, i went to let it warm up the other day and i noticed that when i turned it to heat and high, nothing happened. all i get is a little bit of air out of the defrost up front, and it only works while im moving, it wont blow any air while it sits in the driveway getting up to temp.

the blower fan fuse is still good, the temp works, if i put it to cold it blows cold, warm it blows warm (like i said it only has any airflow while it is moving) no matter what speed or setting i put it on all i get is slight air movement in the defrost vents. I was wondering if anyone has had a similar problem and could help me find where to look and what to do to get it going again.

 

Sounds like your blower is not working,wire it to the battery and test if will come on,if it does then it is either the switch or resistor behind the glove box. If the fan works when connected to the battery,then check for power to the switch and from when any speed is selected. If there is power there then will need to check resistor.
If blower does not work then replace it.

 

That happened to mine once so I unscrewed the instrument panel and the heater buttons and sure enough a wire was disconnected behind it and after I connected it I was able to choose how much heat blows out instead of the tiny amount that would blow out before. Its worth a try!
My Jeep heater is amazing... I put the on fan on full, the heat on high, and leave it set to vent.. It warms up my Cherokee in about 1-3 minutes even on a freezing day