heater, defroster problems

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by joeg, Jun 21, 2010.

  1. joeg

    joeg New Member

    Hello to all of you Chevy Pickup Fans.

    I am having a problem with the heat/defrost controls on my 2004 Chevy Silverado Z71. It is stuck in the defrost position. I thought the problem was with the controls so I bought a new one only to find out that was not the problem. I dug a little deeper and found that the mode (heat/defrost) had become uncogged. The actuator had motored so far that the defrost gate was stuck.

    I bought a new actuator, a Dorman, online and tryed it. I can not get it to activate. I checked the brown wire to the actuator and it has 12v. Checked for continuity from the control modual to the actuator and all of the wiring is fine.

    Not sure what the problem is. Is the actuator the wrong one, or is the problem in the controls?

    Any advice would be great.

  2. 04-silverado

    04-silverado Rockstar 100 Posts

    Similar but not identical problem on my '04 Silverado 1500 2WD 4.8L ...

    Shortly after buying it (used w/97Kmiles), the A/C would suddenly QUIT and no matter what I did with the controls, it BLEW HEAT (not just outside warmed air, but HOT air as if HEATER were requested). After a short trip home, with HEAT trying to kill me... I shut off the truck and began looking for blown fuses related to the A/C. I got distracted (a wife of 40 years can do that easily)... and after 10 minutes or so, returned to the task at hand. I found nothing wrong and the next day the A/C worked for a short while... then the HEAT returned?!

    Anyway, after searching these forums I came across this solution:

    * key OFF
    * open the FUSE panel just inside the driver's door
    * remove the 10 AMP HVAC fuse (it should be GOOD, but check it anyway)
    * turn the KEY to the accessories (not start/run) position, leaving it that way for a minute or so
    * turn the key OFF
    * re-insert the 10 AMP HVAC fuse ​

    Doing the above apparently allows the "actuators" to be reset. My A/C has not acted-up since.

  3. joeg

    joeg New Member

    Bingo. I installed the actuator, pulled the hvac and heater fuses, turned on the ignition and waited 10 minutes. Then turned off the ignition, installed fuses and tried it. Works great.
    Thank you 04-Silverado

  4. 04-silverado

    04-silverado Rockstar 100 Posts

    Great... glad that approach worked for you! Sounds like you're a bit relieved... I can assure you I was relieved (ecstatic even) to have found a NO COST solution on these forums. Sure beats the hell out of paying (at minimum) a diagnostic fee... which I surely would have paid (as I just can't be without A/C here in Southeastern VA... too hot & humid to just roll down the windows)! LOL!

    Even though I am relatively new here myself... allow me to WELCOME you to these forums!

    - karl
  5. jdk0503

    jdk0503 New Member

    Hey Buddy , My truck started blowing hot air going up the road , figured I would be pulling heater , dash out . Did not wanta do this and didnt wanta pay to have it done . Tried your fix with pulling the fuse and works like a charm . AWESOME thanks alot . HAve a Great Day !
  6. bigbluesub

    bigbluesub Rockstar

    what is the problem if this only temporarily fixes it. I did it and it was fine. Put it on hot air and then back to cold air, now blowing hot again........thanks...

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