Hello all I have a 01 blazer with some issues with the heater.

The vent controllers stopped working so I took out the dash board and the covers underneath to take a peak inside. In the mean time the heat controller also stopped working since it blows cold air when its on hot. I checked the heater core hoses and both were hot so I know its not clogged.

Which parts are responsible for this?
There is a vaccum operated controller at the center right of where the dashboard is which seems to control a plastic flap. There is another one to the bottom left of where the dashboard is which has a horizontal metal piece thats supposed to move around. The metal piece is not attached to anything, seems broken but regardless it does not move. When I switch from cold to hot or vice versa there is some minor noise coming but I do not see any movement of any kind. When I switch between the vent options I hear no movement or noises at all...


Any clues?
Thanks

 

A quick check to do is make sure the vacuum in the engine compartment (to the right of the brake booster, its a vacuum line connected by a "T") isn't broken off. This would prevent the controllers and cycles from working.

 

I didn't think to check that cuz the car is running fine. I had problems with the vacuum hoses before and the car idled poorly. I will check regardless though

 

I checked the vacuum and the hoses are perfectly fine. What would be the next step? How is the vacuum operated temp controller removed? It wiggles but doesn't seem to wanna come off

 

There is an electric motor that controls the temperature door... Its called a blend door actuator. Known to strip gears and go bad. Its located on the top of the heater plentum, right behind that vacuum controller. Almost impossible to get at unless have tiny hands or remove dash

 

Thanks!
I have found the blend door actuator and waiting on the tools so I can replace it. Two follow ups though:

1- What is the round black vacuum powered actuator that must be taken off to access the blend door actuator? The white plastic thing that it attaches to is broken. Im wondering how I can get access to it to fix it up since nothing is visible.

2- the oem actuator blender is over a $100. Any good aftermarket brand suggestions for the replacement part?

 

All I know is it's called a slave valve, and it operates a slave door. I am not sure what it does. I am having the exact issue with the blazer i just bought. Supposedly you have to pull dash to replace... My actuator is closer to 30 bucks, manual control. I have also noticed that the slave door on mine is jammed, cant move by hand, probably why broke. I was just going to rip my plenum out, and do a complete tear down, clean, and put new parts in it... May as well change heater core and all

 

Does your vent controller work? Mine blows air out of all vents no matter what setting its on.

 

Mine works, my temperature does what it wants. I must have misread your original post. The actuator i pointed out controls hot and cold.... I know 2 common problems on blazers are the vacuum line, which is near firewall and drivers fender, under hood, and the control unit itself... I will be getting into mine more tomorrow, I'll have some better kmowledge once i see how its assembled

 

To get the blend door actuator you need one of these. I got the same set for free from my father in-law.