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Sub HVAC controls not working right

76zimmer

76zimmer

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I can have my AC on and the vent indicator set to blow out the dash vents, but it blows on the feet. If I turn off the AC button, it will blow out the dash vents. Also the defroster sometimes doesn't work right away.

Any ideas?
 
There's a little arm dealy under the dash that moves as the thing changes the doors and such around to get stuff to blow where you want it. On my '92 I had a similar thing happen once. Turned out the clip holding the lever to the arm had come off and the arm had disconnected itself from the lever. Slipped it back on and everything worked again. That said...it's been 6 years so no, I can't explain it better. Sorry.
 
thats a good start, would it be drivers side or pass? thanks AJ
 
I want to say above the driver's side area.
 
thanks AJ....have you ever replace the brake light switch up there?

What a MFer.
 
Nope, never had to do that.

Was it the doodad I mentioned?
 
turns out the electric control unit to move the arm isn't moving far enough to put full air out the dash vents, it will only go to combo floor and dash vent. So I need to take that off and see whats the holdup. Hopefully I'll get to it soon.
 
So the arm and clip stuff is attached? I seem to remember it not moving very far...but I could be wrong.
 
Yes, I can see the motor control unit shaft (to which the arm for the vent door is attached I assume) from the gas pedal side. When I switch the dash control it functions correctly (moving about 1/4" for each selection) to all but the dash vents, and then the shaft doesn't move an equal amount that it needs to, to open the dash vents. So when I get a day to schedule that in, I'll check it out further.

Thansk again AJ
 
Just for the record....

I took the motor control apart that moves the heater box air difuser, and moved the gears in it to move more towards the vent setting. It took a little messing with it to get it back into adjustment, but it works real good now in all positions.
 
Yeah, the flapper door just wasn't closing enough to send the air out the vents, and it was actually overclosing for the defroster mode, so I moved one of the gears by 2 teeth, and now its right on with all the settings.
 
Weird. If I recall correctly on mine the arm thingy just fell off so it did nothing.

Reminds me I ought to fix The Blazer's flapper door. Heat works fine but it doesn't route it quite correctly.
 
I did find too, that the flapper seal was torn, contributing to the problem. I haven't fixed that yet. It works pretty good just by "timing" the gears in the motor control housing.
 
Mine doesn't duct the air completely right and air comes through the dash vents when everything else is running.

However the flow still manages to defrost/defog the windshield and heat the cabin up very quickly so it's not a big issue for me.
Going to get the AC fixed soon though, it's already in the 80's here, so performance when it's really hot might require I fix it sooner than "when I feel like it".
 
right....I've used it a few times up here already too.
 
I tried your little trick on my 95' and it work much better.
The secret is that little blue gear. It seems to dictate where the gears line up.
Keep that one in the neutral position,and adjust the bigger main gear.
 
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