Jack SuperDork
9/16/09 11:33 p.m.

2006 Malibu LT 84k miles.

Just yesterday, the heater stopped providing heat. When the car is up to temperature, the radiator and heater hoses are hot, the temperature gage goes to it’s normal position, but no matter where the temp selector is set, the vents only blow cold.

If the car is parked, when already warm, the first few minutes of running will yield heat, but then it goes cold. I suspect this bit of heat is from the heater core and is seeping around the damper that controls whether the air flows across the heater core or not. I suspect it’s the damper, as there is no sound like a moving damper when moving the hot/cold knob, although I'm not sure it made noise before. Changing from vent to floor to defrost makes a whirring sound.

I’ve pulled most of the plastic pieces from around the heater area around the hump, but stopped short of pulling the actual dash apart, as I’m not sure where the motorized damper is located.

Can anyone provide any guidance as to where this motorized damper is located, how to determine if this is the issue, or am I barking up the wrong tree. Any help (especially a PDF copy of the shop service manual or th appropriate pages) would be appreciated. Unfortunately, I have not found a Clymer or Chiltons for this new a vehicle, only up through 2003, which was the last year before the model change and the Chevy OEM shop manuals are brutally expensive.

Thanks in advance,


Jack SuperDork
9/21/09 10:22 a.m.


OK, so I've located two acutators, but neither looks like what I've found images of on the web. Guess I'll be off to a Chevy dealer to see what I can see today. It would be really nice if the actuator can be changed without yanking out the entire dash. I have the bottom half and the center of the dash out currently.

Any help from GRM out there?

Jack . . . . . and yes, I deactivated the airbags. They are serious looking devices BTW.

John Brown
John Brown SuperDork
9/21/09 1:13 p.m.

Go back one step...

Disconnect the heater core and back flush the heater core to make sure it is not full of DEXCOOL sludge.

Jack SuperDork
9/21/09 2:02 p.m.


Great suggestion!!! I had checked the hoses into and out of the core to verify they were hot.

As I approach 88k miles I have been trying to figure out if I should flush all the Dexcool out, i.e., fill with water several times, driving the car for a day or so in between, then fill with REAL coolant, or just refill with the Dexcool. I'll have to do some searching on this one.

Back to the issue. I went to the Chevy Dealer to get some drawings, which they had. The service dept suggested pulling the codes (Duh, why didn't I think of that?), as well as checking for heat in the hoses. The parts guy supplied drawings adn let me know it's a $50 part. As I got back into the car, I made some threats (to the car) about having the drawings now, the I could dig in with fervor. I reached down to where that actuator was, and turned the heater knob to see if I could feel it vibrating as it moved, and oddly enough I could. I though this was odd, but figured I'd check it out tonight at hom. When I started driving away, the heat was back. Yesterday, I took the control unit apart. This is the control assembly with the knobs. I worked on it and all sorts of electrical connections, but I didn't try hitting the heat again after reassembly, as the control unit tested out OK, as far as my Fluke DVM could see.

The Downside:This could go bad again at any time, so I'm not going to put it all back together again real quickly.

The Upside: This actuator is replaceable without ripping the dash completely off. Pulling the drivers side knee bolster off affords extremely marginal, but likely acceptable access; I think the actuator can be replaced in situ.

Thanks for chiming in John!



AdamDecker New Reader
11/12/09 2:34 a.m.

Under Floor Heating mats are DIY friendly or can be installed by a handyman or contractor. All wiring should be done by an electric professional.

BoxheadTim Reader
11/12/09 3:56 a.m.

Do those heating mats work in canoes as well?

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