my buddy has an 01 blazer 4 door and he has no heat. I have checked heater core hoses, getting circ, and heat there, TStat is fine, checked vac lines, all good there, from what I could tell. looks exactly the same as my 97. when you turn on AC, the door opens behind the glove box. Just not getting heat. you can heat everything switching when you turn the heat and take it to air and back. also, the accumulator(someone help me here, big shiny canister on left side of engine) was freakin cold as HE** with the heat on full blast. Any Idead?????

 

Sounds like the AC is on at the same time. Pull the fuse for the AC and see if the heat works. Then check the switch or the AC relay

 

I have had exactly the same problem and both my mechanic and the Chevy dealer could not locate the problem.

My problem is even screwier as it comes and goes and I have not been able to reproduce the problem when I brought it in for service.

If you get a solution, I would appreciate an e-mail.

Tom@tcisystems.com
98 Blazer - 2Door

 

Hey hillbilly...first off I know you mentioned this, but are you sure the temp door is moving and not just the mode doors? The temp door is the only one on this system that is an electric actuator as opposed to all the other ones being vacuum controlled. you can see it by dropping the glove box down it's on the top side of the hvac case behind the glovebox. Make sure the shaft is rotating as you turn the temp control **** on the hvac control head. If it is let me know and we'll dive farther into this one.

 

I think so, but not sure. is it on this diagram??? https://blazerforum.com/upfiles/2910...233282FF20.gif

 

No that's the mode valve actuator. Let's see if I can get this pic on the post.

[IMG]local://upfiles/3319/5289B4EB1381435687C02645D21BADEB.gif[/IMG]

Yea that's it #1 in the picture is the temp valve actuator. It's behind the glove box.

 

I can hear something else moving up there, its neither of the vac actuators. but the thing is so far up in there, that its impossible to even get off the harness and check voltage.

btw, how is lancaster???? my folks live in HAH, i used to work at the Y for a while.

 

Lancaster is ok..I guess...Do you know Taylor Chevrolet?

So did you get this thing figured out or what?....It sounds like the core is plugged up to me.