Hi all, New to the forum. Just recently bought a 1999 Blazer LT. Now the heat at works and the ac works. But even when the blower motor is shut off I can hear the mixture door switching it from hot to cold underneath the dash.So when you turn the blower motor on it is always switiching from hot to cold. The heater core has been flushed and the control panel has been replaced, and the mixture door module has been replaced. I have hit a brick wall. What else could be wrong? It seems to me that whatever tells the mixture door to do what its suppose to is bad. Though I have changed the control panel twice! Please if anyone knows anything about this let me know. Thanks for your help in advance, Bill

 

There's an actutor under the dash that controls that if you clicking it probley gone bad. u have to replace that. and it will fix it dont feel bad though i have the same problem on my 99 lt model.

 

Ohhh No I did not know that!! But maybe thats what the problem is!!! Or at least we can hope. Now I have another quick question. When ordering this part what actutor should I buy. Is there a speific name? Thnks again! Bill