Dual Climate problem

You may have a variation of what happened to me back in June of this year. From what you have described, you may have a stuck actuator. Here is my experience:

This actuator problem started happening to me about 4 months ago. My 2004 Silverado has dual, sliding temperature controls and the "clicking" and "whirring" problem affected only the left side control. This problem is constant and does not require the AC to be on: Turning the key to the accessory position (with the engine off) is all it takes to get the actuator to start "hunting" for its required resting place. Unfortunately, it is rarely able to find this ideal resting place.

At first, I was able to get the actuator to stop hunting by placing the left temperature slider two clicks up from the bottom position. However, the actuator would continue to periodically start and stop its hunting maneuvers and my guess is that the unit is temperature sensitive. Sometimes, it would only stop clicking when the left control was placed in the bottom position. Finally, it became impossible to get the actuator to stop cycling for an extended period of time. After months of constant cycling, the actuator motor was wearing out.

Yesterday, I finally got around to taking the truck to the dealer. Here is the result of the diagnosis:

Customer reports motor noise from blend door box area with no AC on. Check and advise.

(Cause) Actuator "faulty"

Inspected: (ordered actuator -- 06/27/05)

Fortunately, the truck is under the bumper-to-bumper warranty, so the only expense will be the loss of my time. I hope to have the part delivered on Wednesday and the installation completed on Thursday. This will be perfect timing, since I will be heading into 90 degree territory over the 4th.