randalls9

I have 93 C4 and the heater will not blow hot. A/C blows cold and all fan speeds work as well as floor to mid to defrost settings - just no hot air coming out. I have checked the "heater door" assembly (by removing the huge heat sink from the firewall side) and the door does not move to the closed position when the heat is turned on. It looks like it is trying to move, but just doesn't get closed. I can close it manually and the heat works. I have lubed it, but still nothing. I have tried to get a good look under the pass. dash, but it's so tight down there I really can't see much. Anyone have any experience with this - any suggestions?

THANKS!!!!

GM Junkie

Lots of info here on this subject - do a search. It makes a difference whether you have auto or manual climate controls. Good luck.

gbrtng

Manual air has a Bowdon cable to the mixer valve. OP's is obviously an auto air unit. Take the glove box out, first the door, then the box, and you can see the mixer valve. I just got done working on a 91 manual air car, and it's very tight, but you should be able to replace the mixer valve motor (with a little luck).