Temperature Door Actuator?

I have a 2000 Sierra with a strange problem. If I turn the temperature control knob all the way to hot the heater works fine but if I then turn it all the way to the cold side the fan continues to blow hot air. If I turn the knob to cold before the engine warms up the air conditioner will blow cold air. I was told this was probably the temperature door actuator and the dealer would charge $150 to replace it. Can anyone tell tell me how dificult this is to do?

I have the same problem. Have you figured out how to do this yet?

I had the same problem with my 95 Sierra. It is one of two things, the actuator motor located above and to the right of the gas pedal, or the heater control itself. I replaced the motor first, didn't help. About 50 bucks shot.! Next up heater control, 100 bucks. Bingo. Found heater control on Ebay. Dealer wanted 150 plus. The place I ordered the was also a dealer, but was cheaper. I can give you the name if you need it.

I figured it out evetually. It was the LOWER actuator door. I bought it on line at gmpartsdirect. They have really good prices.

The install was a bit tight as one of the screws/bolts was a little tough to get to but with a little patience, it went very smooth. Haven't had any problems since!

Thanks!

Happy New Year!!!