2nd Gen Non-Engine/Transmission Heater Control not working Help

[Bob Cochran]

I cannot control the heat or cooling with the knob. It is either all cold(icicles) or all hot(sweating) nothing in between works. You can have it all the way to max cooling and as you move toward hotter it stays the same then goes all the way hot. The same the other way to hot to cool. Is this control a reostat? Anybody else hav e this problem? Could it not be working? Suggestions on what it is and how to fix?

 

[jgallentine]

Bob,



The blend door is controlled by a little servo motor on the bottom of the vent. There is a plastic coupler between the motor and the door. I have a 1999 and I experienced the same problem you are having, the plastic coupler was broke. The kicker is you are supposed to take the airbox out to get to one of the screws to get the servo motor off. This would mean taking the steering column and dash out.



I was able to take the one screw out that is easy to get to and loosen the other a couple of turns with a short 90 degree bent screwdriver. The second screw is right up against the transmission tunnel. This allowed the servo to be pulled down far enough to get the coupler out. When you put it back together, the servo has to be synced with the door. Before reattaching the servo, unplug the wire harness from it. Turn the key and the a/c/heat on. Put the temperature control know in the middle 12:00 position and plug the servo back in. The servo should move for a bit and then stop. At this point, when you move the temperatue knob a notch or two the servo shuld move with it. Put the knob back in the middle 12:00 position, line the blend door up with the servo and reassemble. I am sure this is not the only thing it could be but it worked for me and hopefully it will work for you.



I have been told that there is supposed to be a key between the servo and the blend door but mine did not have one, the parts book did not show one and the new collar did not come with one. I fixed mine almost a year ago and it has been fine since.



Good luck.



Jeff

 

[Bob Cochran]

jgallentine Oh this sounds like fun!!!! I have a few more smaller and easier jobs to do yet on the truck. Think I will do this one last. Thanks for the help.