Like many of us gmt800 owners I’ve had blend door actuators crap out on me. My system has the dual zone with sliders to adj temp. Mode and defrost still working for now. Replaced drivers side years ago and still working fine. Passenger side (managed to replace without dash removal or duct mangling) replaced with Amazon crap and failed, then AC Delco straight from Korea a while back. working fine until recently.

My experience has been when they go they sit on full hot. Recalibration sometimes resets when they do, no such luck this time. Now I have a different problem. Passenger side is sitting at a middle temp, and when I swapped a new actuator the pin the actuator slides onto in the actual blend door free spins. Usually you can move the door by hand and feel it hit open and closed position.

Thinking I actually have a broken door, which means disassembling the dash to get the hvac box out. Massive pain, but most likely worth doing myself rather than shelling out more than a grand for a shop to do the work. I’ll just have somebody recover and replace refrigerant for me.

question is how far do I go? Rather not tear it down and replace just the door only to have the evaporator or heater core have issues later- all original as far as I know.

Full Monty would be:
blend doors
recirc and defrost doors
evaporator
Heater core
Mode actuator
recirc Actuator
blend actuators
blower motor/fan/resistor



Thoughts?

 

"Thoughts?"

Drain coolant,
detach exhaust,
Pull the motor.
CUT access door in firewall.
Change heater core through your new access door.
Blend door access from top "dash panel" it's going to crack, just let it... Re-install as a two piece with a nice custom "trim strip"

 

Wow! Pulling the motor and cutting the firewall is certainly an aggressive approach!!

Certainly would’ve been nice if GM had made it so hvac was more accessible. I may use my fiber video boroscope to look to confirm a broken blend door.

Assuming I pull the hvac box, my question is:
full refurb of all parts or just replace what’s busted?

 

I'm a just replace what is broken guy. It is hard for me to replace good parts with maybe good parts...

 

I thought they sold aftermarket aluminum blend doors, no?

My 99 Silverado had the heater core replaced back in like 2010-iirc. Everything is still working good. A few months ago I had an issue with my temperature blend actuator making a thumping sound, but I removed and took it apart and reinstalled it and that went away.

My 06 Suburban had the heater core replaced about 3 years ago. That one has the Auto control, which I'm not a big fan of. I did replace the little sensor that's on the driver's side headboard because the temperature control didn't really work. Otherwise everything works well.

If you have a bidirectional scanner, you can try manually overriding the controls to see what's going on.

 

Shake, I hear ya and normally I’m the same. Just sooooo much work to get to all of this stuff.

This may be the time to snag a bidirectional scanner as I don’t have one currently, good idea to confirm door vs actuator. Now to research a reasonable knock off tech2.

Aluminum blend doors I have not seen in my searching, but I’ve not looked beyond Amazon or rockauto.

edit- found the aluminum blend doors, nice but fairly expensive. $400+ for a full set from the one place I could find that makes them.

 

Absolutely agree. That’s a huge *** job. Hard not to


But you know what they say, once you’ve done it once you can do it faster the second, third and fourth times LOL

 

It's a door pull the dash take it apart and change it IF you can find the parts gm has discontinued the hell out of parts for those trucks. I havent had to do one in a couple years and I played hell finding all the parts then. Replace all the doors, evap and heater core 03-5 notorious for evaps and all of em had heater core problems especially once you disturb them. GM parts are expensive but they are the better of the non optimal parts situation we have these days. Order a case foam kit for a 11 or 12 to replace all of the case foam seals that seal to the fire wall and dash to ductwork and max air plenum to the cowl.

The only way to do it is remove the dash no way around it I've lost track how many I've had out since 99 when these trucks came out. If there was a fast or shortcut I'd know it and there are none.

You are at the bridge in the water point You have to take the time to do it right bend over and spend the money and time or trade it in for more modern stuff you can get parts for.

 

Thanks for all the suggestions! Good to hear from someone experienced in dealing with repairing these. More or less committed to doing this myself and refurbishing the whole box as best as I can. The suggestion for the seals from a later model is great!

Discontinued parts are a pain, struggling to find GM or ac delco evap. Everything else seems to be obtainable. Probably going to use the aluminum doors, about the only way to obtain all the doors and should last.

 

What a pain in the *** that was! All done save for having my local shop recharge the ac system. The dash cover was like saltine crackers it was so brittle. Thankfully it only broke some and more or less is still intact.

Replaced the doors with very nice aluminum pieces from blend door USA. The broken door was obvious once I got it all apart. New actuators all around, but left the fan motor and resistor alone.

the seal kit has been discontinued and I improvised with some closed cell foam I had. So learned there are several bits that need to be transferred over when replacing the evaporator core and receiver/dryer.

The dash was a pain coming off and going on, as was the hvac box itself. It think most of my time went to wrestling those two into position!

Well, it’s done now.