GM G-body HVAC: heat on one side only

[David Bacheller]

For the few of us out there still driving a GM G-body car (Olds Aurora, Buick Riviera) I solved a problem and thought I would pass along the fix. I believe this applies to a whole bunch of vehicles:

I had a common problem of heat on the passenger side, but no heat on the driver’s side. A bit of googling and the idea of a heat blend door actuator seemed to be the most common diagnosis. I took the plunge and ordered up an appropriate actuator from an online vendor, and assumed that my diagnosis was correct.

On the day of actual automotive surgery, I removed the cover panel under the driver side dash. Without belaboring the fine points of the awful experience of working under a dashboard, I’ll pass along a few findings:

Be sure you have located the actuator that you really want to remove. I started working to remove one actuator, when I found that in fact, it was the actuator for the floor/dash/defrost blend door, which was working fine. After determination of the correct actuator (which could be called the “middle” position, when viewing from under the dash) the removal of the electrical connector and then the three mounting screws was straightforward, if a bit frustrating. For hand access, I removed the floor heat plenum and ended up breaking some of its plastic retaining tabs. Oops. For now, I have decided to live with the missing plenum. Heat still comes out to warm my feet, if a bit less directed.

In my case, there was no need to remove the dash. Yea! But working under a dash is still hateful.

I have read elsewhere on the interweb that it is a good idea to finish your installation including the electrical connection, before starting the car. Not sure why, but that is what I did.

Lady luck was smiling, and upon firing up the supercharged 3.8 liter, and warming the coolant, there was controllable heat flowing to the drivers side, as well as the passenger side.

I did disassemble the old actuator and found very quickly a broken plastic gear in the internals, no doubt the reason for my lack of heat when called upon. The actuator was trying to move the blend door, but could not due to the defective gear.

I’m still considering a cludge to reattach my broken floor plenum. But for now, I’m living with things as they are.

I hope this is helpful to those with a similar kind of problem.

Topic

[college man]

Thank you for sharing. 🙂

[John Hugon]

Thanks for bringing this up, especially this time of year when the heater is needed. Of course it’s an A/C issue also. Not just the “G” body shares that issue…all the GM cars and trucks have the issues and you shaved some cost doing it yourself. Just in case anyone is interested you can buy just the gear on line.

[David Bacheller]

Excellent point. Could you provide a link or hint as to where to find the gear on line? The actuator complete was about 80 US dollars. Just the gear would save some more moola.

[John Hugon]

Sorry for not getting back quicker…I found this one on Ebay:
http://www.ebay.com/itm/like/171384359235?lpid=82

[Lorrin Barth]

What is the actual name of this actuator?

[John Hugon]

HVAC Blend Door Actuator

[Lorrin Barth]

[quote=”JTF” post=117284]HVAC Blend Door Actuator[/quote]

So, am I to understand that there are two blend doors, one for each side of the cabin and the actuators are the same for both?

[John Hugon]

Yes, I found this site to explain it better than I can:…Scroll down to dual zone
http://www.agcoauto.com/content/news/p2_articleid/121

[David Bacheller]

There are lots of actuators. On my Riviera’s driver’s side there were three. I did not look at the passenger side. And the “heat blend door actuator” for the drivers side is not the same as for the passenger side. At least that is what I found from my interweb research. Hope this helps.

[Author]

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