Last week had my 96 Blazer in the shop for a rear axel issue and, I ask the guy to look at why I was not getting any heat out of the vents. He called me back and said that he had used a bore scope and found that the eletric motor that controls the blend door had shorted out that and the wireing was shot all the way back to the controls. He told me he had pushed the door open so I would have heat. Now that I am driving this thing I have noticed that some time when I hit a bump my air turns cold then when I hit another bump it turns hot again. Any ideas? dosent sound like that motor is bad to me maybe a wire/short issue. I dang sure didnt like the $800 quote he gave me to replace the eletric motor

 

Depending on your model you can get to the actuator by access from the glove box removal. If it is in fact the actuator. See if your heater core lines are both the same temp after warm up. The two hoses going to the fire wall. One from the intake the other from the water pump. If not drop me a line we can go from there.

I just fixed my heat problem is was not the actuator. I had a gasket leak dumping anti into the exhaust. Fixed and heat galore.

 

I put a new thremostat in it two weeks ago and back flushed the heater core. When the air heats up it is very hot. I dont understnad how a blend door that is attached to a burned out motor(as I was told) can move. And the glove box is built into the dash it wont come out by itself.