Mode Actuator Repair/Replacement

[Supercharged111]

HVAC Actuators: Do Them All Proactively

Howdy, Been troubleshooting my AC and narrowed it down to a failed heater valve and blend door so the heater would run at the same time as the AC making for all sorts of conflicting data. While I was in there cleaning the evaporator core I found the recirc door doesn't fully close so that's...

www.gmt400.com

I found this thread and @AK49BWL mentions springs and retainers falling out and causing the vent and defrost to never turn off. Sounds like that might be my issue and I can't get any air out of the floor which sucks with CO trying to have actual winter temperatures. I understand the mode Actuator is the easy one to get to at the trans hump, but I'm wondering what to look for with these springs and retainers and how to know by looking or poking around whether or not that's the case.

 

[AK49BWL]

If nothing is coming out of the floor, the mode actuator itself is suspect, as it moves the floor door directly. There's nothing between that floor door and the blower fan to obstruct those vents. As far as the springs and retainers, there are arms that attach to the mode door to also open and close the defrost and face vents, but they're all controlled by that one actuator. Someone else here had a nice clear picture of what it should look like, I wanna say east302... Ah yes here we go. https://www.gmt400.com/threads/no-heat-not-sure-what-the-problem-is.64912/post-1362250

 

[Supercharged111]

Thanks, I'll put eyes on that in a bit. I think I have a mode actuator kicking around here somewhere too. Is there a calibration procedure for the actuator?

 

[AK49BWL]

Nope, plug n play.

 

[Supercharged111]

So much easier than the Envoy!

 

[Supercharged111]

Well crap. I just cycled the thing end to end and the actuator actuated and the arms and springs are all intact. Makes me think something else is amiss. Something that's gonna require. 100% disassembly to find.

 

[east302]

If the actuator is turning completely between the hatch marks on the housing and the linkage is intact, then it’s probably worth taking off the floor vent cover to watch the floor damper turn. Maybe something will stand out as there really isn’t much that can block air flow. It’s the damper attached directly to the actuator.

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[AK49BWL]

Yeah, and I'm guessing it's probably the same for most of these but mine has one 7mm screw on the front and two clips in the back in order to remove that cover.

 

[NMNorsse]

LMC lists 3 different actuators- one for the mode door, one for blend door and one for air inlet. Others have said mode and blend motors are the same.

I am looking for the air inlet actuator for my '88 because it is out of stock or no longer made. In the course of that search I looked at some GM parts websites, probably run by a dealership or GM, and one them had the arms/springs for about $25 each, if that is what is causing your issue.

 

[Supercharged111]

My issue is that air is always coming out the middle vents. I suspect this is robbing enough to prevent defrost and floor from being as effective as they should.