I have a 97 Cherokee se and the heater blower only works on high and when I flip it to defrost the door in the heater box slams shut and won't allow any heat to come out of the defrost ducts. My question is what could be the problem? I'm gonna assume its 2 different problems but I don't know where to start looking. Any help would be appreciated. Thank you in advance.

 

blowing on high prob is the blower motor resistor, other prob sounds like blend door prob search it in the search window

 

Thank you I will check it over this weekend and see if the resister is bad and then check for vacuum leaks. I appreciate the help.

 

Check your vacuum lines that go into the fire wall and down to the bumper they are located on the top passenger side