Which actuator?(HVAC)

[71chevmal]

Did some searching here and I guess this is a pretty common issue. I have a 2004 Yukon with the auto HVAC control. I get no heat in A/C mode on both driver and passenger side and with the A/C off, I can feel hot air blowing on my feet but nothing on the passenger side. I did some looking online elsewhere and there was a procedure where they recommended pulling the HVAC fuse under the hood and leaving it out then replacing it and turning the A/C up to three times but that didn't seem to do anything. It seems there are three actuators but how would I know which one was bad? Or are there more than one bad? Thanks

[71chevmal]

Well, I got 2 out of 3 screws out of the lower cover on the passenger side off. And whoever designed that thing should be hung, drawn and quartered.

Anyway, I got it to the point where I can see the actuator attempting to move when I change the temperature. Hopefully, that's the only issue and not something bigger.

[Cusser]

Originally Posted by 71chevmal

Well, I got 2 out of 3 screws out of the lower cover on the passenger side off. And whoever designed that thing should be hung, drawn and quartered.

Anyway, I got it to the point where I can see the actuator attempting to move when I change the temperature. Hopefully, that's the only issue and not something bigger.

Yeah, the hump is in the way !!! I was able to get this cover off, only replaced the two screws after the repair.

Just wait until you try to get the 2nd screw of the actuator off; let me help you because you'll need to grind a 5.5mm 1/4-inch drive socket shorter at both ends , because - guess what - the hump is AGAIN in the way !!! See the last few posts in this thread:

"In my limited driving on 2005 Yukon I had noticed that the AC changed by itself to heat on driver side, and there was clicking under middle of dash. One could stop and turn engine off and that would re-set. Apparently this is due to a faulty door/flap actuator under the dash, and is a common problem on Yukons, Suburbans, GM trucks. So I took off the underside cover, of course being GM the innermost bolt was like impossible to get to, dug out a 7mm deep socket and was finally able to get that (read posts about folks having issues with that, and just leaving that screw or cover off). Anyway, that actuator has 3 positions, and I got it into the AC mode and then unplugged the harness so we'd have AC. But it turns out that this meant no heat.

Santa brought Mrs. Cusser a new aftermarket Dorman actuator ($50, why buy more-expensive GM again when there is a trail of bad ones posted on Internet?), and I braved our 45F wind-chill yesterday to install it, actuator is held in by 2 hex head screws. Well, once again, cannot access one of the screws due to the center hump being in the way, what terrible engineering. The screws take a 5.5mm or 7/32 inch socket, and I had to grind down BOTH ends of the socket to shorten it (recessed, so no access to use an open end or box wrench, had to use the ground-down socket and a 1/4 inch ratchet wrench; no room to fit in a thumbwheel-type 1/4 inch ratchet either


Anyway, (using online instructions) I set the flap to align with the position of the new actuator, and bolted that in, reconnected the harness to the actuator, reconnected the battery, waited a few minutes, turned the ignition switch to on for a few minutes so computer could learn stuff, then switched ignition off for 10 seconds. So now we have both heat and cooling. I left the lower cover off, don't see any real reason to reinstall that.


Thanks again, GM !!!! What a poor design. I know a shop gets $300-$400 for replacement of these, had it done at a shop on the 1994 Suburban, and remember the mechanic saying how much of a pain it was !!!"
http://www.automotiveforums.com/vbul....php?t=1143054

[71chevmal]

I got it replaced and it seems like the actuator did the trick.

The gold colored screws are 7/32" (1/32" under 1/4") and the black screws are 9/32" (1/32" over 1/4"). I struggled a long time before I figured out they used a different screw in that position. I have a fiber optic "snake camera" attachment for my phone so I could actually look at what I was aiming at.

Heaven forbid they just go with 1/4" for everything and then any normal person could work on these.

And you're right, the screw over the hump goes into the trash when you get it out.

The second actuator screw wasn't horrible. I used a regular socket and a 1/2" long extension.

I think I could probably get it done in about an hour or so now that I know what I'm doing.