I've been doing some research on heating problems for my 99 sport. Well I've been looking for vacuum problems, with the blend door (the flap the either lets the heat in or cool) since i get heat some times and sometimes not. Come to find out on 97-01 cherokee's there is a electric motor the opens/closes the flap and the motor is notorious for failure and i think this is my issue.

Anyways i havent dived full into it but played with my dial for heat and if i go slow i get heat if i turn it fast to heat it doesnt get warm so that points to bad/weak motor i think??

Anyways a cheap free fix to this once i confirm it would be to take motor out and manually put flap to heat in winter and cold for summer and leave it?? Like i said i havent tried it to confirm but if anyone has or has any more info to help me and others it would be appreciated!

Here is the website I've read about the issue and it tells you how to do it!

http://www.heatertreater.net/jeep%20...e%2097-04.html

It trys to sell you there product tho but gives good infor

Thanks for the link.