Vehicle - 1998 Blazer LS 4WD, manual temp/AC controls
Symptom - Heater blows or trickles hot air all the time, even when turned to the off position. Will not blow a/c cold, though a/c tests good. Hot air will blow where it is supposed to i.e. - defrost vents, floor or dash.

I have read a few threads here and elsewhere, such as:
https://blazerforum.com/forum/tech-articles-diy-29/how-2nd-gen-blend-door-actuator-replacement-29981/ and
http://www.automotiveforums.com/vbul...d.php?t=574779 .

If it is the temperature actuator, can anyone confirm this is replaced through the "center control panel" where the switches are located as indicated in the first thread listed? I couldn't quite tell. In addition, what is the part number and a purchasing source for the part.

If it is the blend door, while I dropped the glove box, I still couldn't locate the part. I will post pictures if this is the issue.

Great forum, total newbie, shade tree mechanic. Thanks for being here for us "idiots"!
Mark

 

No, it is definitely not replaced through the center... It is on top of the HVAC ductwork towards the passenger side, accessible by dropping the glove box down.

I have to get this thread updated. The pictures were lost in my last server move for my personal website.
A/C Evap Core Odor - Here's the fix!

I think those pictures show the location of the actuator though.

And never sell yourself short by using such a word!

 

Thank you for the prompt response. Unfortunately the pictures were not available.

Do you think the problem is blend door or temperature actuator?
If blend door, I still don't see how to get to it through the glove box. Here is a photo of what I see and have messed with behind the glove box.

I truly appreciate the forum's expertise and assistance!

 

It is further up to the right looking at your picture. If I remember correctly, you need a mirror to see it, but there is enough room to get your hands in there and with a small enough bit, you can get the screws out.

The blend door is moved by the temperature actuator.

This schematic will illustrate which door performs each function:


So as you can see, you could either have a problem with a broken blend door, or an improperly calibrated or defective actuator. You could run through the recalibration procedure... I cannot look it up for you right now, but I know it has been posted before.

 

Precisely! The learning curve is a little steep, I'm clinbing it myself right now, but have faith it can be overcome!