Permanent Heater

[Rottwiener]

I have a 1998 Blazer LT, 4D, 4WD. Hot air always comes out of the floor vents; even when the control selector is all the way to cold and even when the air conditioning is on. It has the manual heater/AC controls.

I've read the helpful How To posts about the "blend door" and its actuator, but I don't think that's my problem. (It would also probably be helpful to include a more descriptive title to that thread so people who don't know it's called the blend door can find it.)

The symptoms are the same - always hot air coming out of the system - but when I checked the blend door actuator, everything appears to be working exactly right. I can feel the motor activating. I can hear the door itself sliding in the duct. And I can see the shaft from the actuator motor rotating.
Is there some way the blend door could be out of alignment or something like that which allows the hot air to by-pass it even when it is closed?

Any guidance before I start tearing apart the dash would be greatly appreciated.
Thanks.

[MT-2500]

Year and auto or manual ac controls.
Give us a good description of what it is doing or not doing.

[Rick Norwood]

Originally Posted by Rottwiener

I have a 1998 Blazer LT, 4D, 4WD. Hot air always comes out of the floor vents; even when the control selector is all the way to cold and even when the air conditioning is on. It has the manual heater/AC controls.

I've read the helpful How To posts about the "blend door" and its actuator, but I don't think that's my problem. (It would also probably be helpful to include a more descriptive title to that thread so people who don't know it's called the blend door can find it.)

The symptoms are the same - always hot air coming out of the system - but when I checked the blend door actuator, everything appears to be working exactly right. I can feel the motor activating. I can hear the door itself sliding in the duct. And I can see the shaft from the actuator motor rotating.
Is there some way the blend door could be out of alignment or something like that which allows the hot air to by-pass it even when it is closed?

Any guidance before I start tearing apart the dash would be greatly appreciated.
Thanks.

My 2000 Jimmy does the same thing. I've been told by two different Dealerships That there is nothing that can be done about it unless you want to install a manual inline valve the heater hose .

[Rottwiener]

Thanks Rick.

I had thought it was just the common blend door problem that I learned about here, but that doesn't appear to be the case. What it really seems like is that the blend door is not closing all the way. When I turn on the fan, there is a dramatic difference between turning the knob to "Hot" and turning it back to "Cold", but even so, it's always hot.
Last Summer I got a step-down line splicer and just looped the heater hoses, bypassing the heater coil, but the splicer blew half way to the beach. Luckily I had the parts to put it back to normal with me. From that experience, I don't trust plastic parts at all for such purposes and I'm looking for a good, brass ball-cock to stick in the line.
Still, I'd love to find a way to actually repair the problem.
Best,
Sam