Envoy auto climate control problem- only hot air *solved

[gcstandi]

i have an 00 with computer climate control. the fan and vents/floor/defrost work fine...except for all i get is hot air. with the fan off and temp set to cold, i still get hot air being forced out the vents. its like a heater valve is stuck open. the air door actuator was acting up (constantly opening and closing even with the hvac off) but that's sense quit.

in a possibly related note, i did find two wires attached to a green plus hanging on top of the passenger floorboard. it looks like they used to connect to something, but i've searched for two days looking. the wires are pink and grey. could this be related? my heat prob started about the same time. the wires have no power to them, so whatever they plug into must power it (im hoping that it controls that heater valve).

im in kansas and its starting to get hot. if i wanted to sit in a sauna, id go to the gym!

i've searched and read lots of posts, but no one seems to have the same problem, although the hot feet problem is what im experiencing now, i just have the auto climate, so i can't do that fix.

thanks. you guys are smart, so i bet you know what my prob is.

[F9K9]

i......... the air door actuator was acting up (constantly opening and closing even with the hvac off) but that's sense quit...............

That is a good clue to check out.

Have you had the AC system checked out anywhere, yet?

[HenryJ]

Check for vacuum leaks. Look closely at the dry rotting lines behind your power brake booster.

Is yours autotrac four wheel drive?

Make , model and year (2000) please.

[gcstandi]

i'll doube check that area for vacuum leaks. i did pull off some lines to the underdash unit and all had decent suction.

yes, it has gmc's version of auto 4WD.

2000 gmc envoy (just like the jimmy, but more problems i think).

i took a picture of the dangling wires this morning. you don't seem to think the wires are related?

[HenryJ]

Moved to NOS since it is not a crew cab issue.

Still waiting on the picture.

[AZS10Crew]

Maybe a bad blend door, blend door motor, or even cracked blend door case. That was a very common issue when I worked at the Ford dealership. The blend door controls how much hot and cold air are directed to the vents and moves back and forth based on temp settings.

Could also be a bad climate control head unit. If there's an internal problem in the head unit it might cause the temp to not adjust.

Only way to know for sure is to do pinpoint test on the motor and the head unit. Or just start throwing parts at it.

[gcstandi]

well. i checked the vacuum lines by the brake booster. had to figure out which ones went where. (one goes across motor to 4wd system- i think; one goes to a plastic deal attached to the inner fender-deadends; then one goes into the firewall to the interior).

the vacuum line that goes to the interior has a short rubber line, then attaches to a clear-ish hard line then goes into a wire bundle and i lose it from there. that's the right line right? if so, all lines look good. i think ill go back into the interior and start tearing that up again. ill look at the door actuator--any good tips on how to test it?

[HenryJ]

I received your pictures. That wire is for the Cellular telephone external speaker. They are output wires.

Nothing related to your HVAC issue.

[gcstandi]

Well, that's great news. I can finally get some sleep. (Seriously, how do you know that? Impressive.)

I tore back into the evaporator unit today and removed the door actuator. The plastic ring gear is split in two spots. And the actuator continuously turns to keep the door to the hot side. Once it was removed, and the car/vent on, I manually turned the door counterclockwise and it instantly blew out cool air. Then, if I turned it clockwise, suction pulled it the rest of the way and instant heat. O'Reily had an actuator--it looked identical, but was for 4 wires and not 5 (as mine is). So, I think I'll just suck it up and order it from GM dealer in town. With the plastic ring broken and (fingers crossed) the actuator acting up, hopefully this fixes the problem.

Anybody else ever have this happen? Or is the actuator only doing the dirty work of something else that is going haywire?

[HenryJ]

Well, that's great news. I can finally get some sleep. (Seriously, how do you know that? Impressive.)

Thank you. Not too tough if you have a manual to browse. It is listed in the connector end views. That connector is unique , the location, the wire color and only two wires in the connector made it pretty easy to identify.

[AZS10Crew]

Anybody else ever have this happen? Or is the actuator only doing the dirty work of something else that is going haywire?

Sounds to me like you found the problem.

[GeorgesBlazah]

I had to replace my blend door motor, but I would replace the controls before I did that. It was a pita to do it.

[gcstandi]

Well, I replaced the air blend door. It was much more expensive, as the Envoy has electronic controlled actuator (other S-10s with non-computer controlled climate must have a vacuum operated actuator).

it fixed the problem instantly. hope this helps if anyone else has this same problem.

Thanks for your help. Now for a tranny filter change.

Greg

[HenryJ]

Great news!