Vent stuck open???

[leah664]

I have a used 2001 LS with rear air. I love my van, but since this will be my first winter, I hadn't really used the heater - just the A/C which works great! So now I realize that although the rear heat is working fine, the front is not hot...it's like it is trying (blows fine) but there is a cool draft mixed in. Well, it seems the switches on the lower part of the heater (outside air & recirc) are stuck. The light that indicates "fresh air in" cannot be turned off. So is my vent stuck open then? Makes sense to me, that would explain the cold air mixed in with warm. My hubby took heater contol out, looking for a bad sauter, etc, but it looked fine? What other reason would I be unable to switch to re-circ? Should I try to buy a used control and replace? Any info appreciated.

Leah

[cdru]

What position do you have the vent selector? If you have it on defrost or defrost/floor, it will be forced to fresh air intake. The other positions should allow you to switch between different intakes.

[leah664]

I have tried all positions. Makes no difference. I cannot get the light to turn off of the "fresh air" button. It's getting cold now and I have the floor heat cranked up, but still have the cold air coming in. Thank god for the rear heater or we would be totally freezing until I get this sorted out! Gonna try replacing the heater control ( just used from a wrecker) and see if that makes a difference. No way am I gonna go through the dealer...they quoted me around $600 (canadian) to replace. Wrecker has some for around 70 bucks....wish me luck!

[GregA]

Originally Posted by leah664

I have tried all positions. Makes no difference. I cannot get the light to turn off of the "fresh air" button. It's getting cold now and I have the floor heat cranked up, but still have the cold air coming in. Thank god for the rear heater or we would be totally freezing until I get this sorted out! Gonna try replacing the heater control ( just used from a wrecker) and see if that makes a difference. No way am I gonna go through the dealer...they quoted me around $600 (canadian) to replace. Wrecker has some for around 70 bucks....wish me luck!

Before you spend that much $$, make sure you check ALL the fuses in the fuse console (side of dash on the passenger side) related to A/C & Heater controls.

In particular, check fuse # 46 (see fuses here). This fuse supplies power to the controls for the front side.

Also, there is a common GROUND for all the front actuator motors (including the temperature and recirculate doors). According to the (factory) manual I have, it is supposed to be :
"Right side of the Instrument Panel (IP), secured on the underside of the cross car beam, left of the heater-A/C vent." This is G200 (Ground circuit # 200).
To see it would probably mean removing the insulator panel (no big deal) and the glove box (several screws to remove).

What I would do is: turn the ignition ON (do not start engine) and move the controls, one at a time, then LOOK & LISTEN for the control motors moving. Again, you will have to remove the insulator panels to see and hear what is going on.

I will look at the schematics and descriptions in the manual some more and let you know if I find anything else that might be helpful.

Take Care,

[leah664]

Thanks for the info, Greg.

I will relay this info to my hubby, he had already checked the fuses, but maybe the other info will help narrow it down.
I am thinking it is a faulty switch as I cannot turn off the one switch no matter what. That damn red light keeps shining!
Oops...noticed I said it was a 2001...its not...its only a 2000.
(sorry! Hope that doesnt change things much!)
Hey Greg - are there any test procedures that you know of for the heating control panel in your factory service manual? My hubby is an electronic tech...maybe if we can get a hold of a schematic we can track this??

[GregA]

Originally Posted by leah664

Thanks for the info, Greg.

I will relay this info to my hubby, he had already checked the fuses, but maybe the other info will help narrow it down.
I am thinking it is a faulty switch as I cannot turn off the one switch no matter what. That damn red light keeps shining!
Oops...noticed I said it was a 2001...its not...its only a 2000.
(sorry! Hope that doesnt change things much!)
Hey Greg - are there any test procedures that you know of for the heating control panel in your factory service manual? My hubby is an electronic tech...maybe if we can get a hold of a schematic we can track this??

Oh - a 2000. I think that is a little different, but not too much.

My 2001 has TWO buttons - one for Recirculate & one for Fresh air. Do you have the same?

You may be right about a faulty switch (or control module). I will see what I can gather, information wise.

Check your PM (Private Messages) for a note some time soon.

Take Care,

[leah664]

Yes - I have two switches...one for fresh air and one for recirc.
(fresh air is the one stuck on)

Thank you for all this stuff! Our Haynes manual is very non-specific, so these items will really help.

My hubby thinks it's one of the electronic components on the HVAC control circuit board, however, GM in-house part #'s inhibit circuit board testing and diagnosis as there is no cross reference to regular part/chip numbers.
Thanks so, so, so much for all you have done! Wow. Nice to know the world has people like you out there!
Will let you know what we find.


Leah

[GregA]

Originally Posted by leah664

Yes - I have two switches...one for fresh air and one for recirc.
(fresh air is the one stuck on)

Thank you for all this stuff! Our Haynes manual is very non-specific, so these items will really help.

My hubby thinks it's one of the electronic components on the HVAC control circuit board, however, GM in-house part #'s inhibit circuit board testing and diagnosis as there is no cross reference to regular part/chip numbers.
Thanks so, so, so much for all you have done! Wow. Nice to know the world has people like you out there!
Will let you know what we find.


Leah

You're Welcome.

I'm just using the gifts I have been given to help out. I hope that others will do the same.

Once you have it isolated to the control section, you should probably head to the junkyard to see about a replacement. If that is the control module I think it is, it was over $200 at rockauto.com - so I would guess about double that at a dealer. eBay might have some too.

Take Care,