02 Tahoe mode door issues

[smiggs]

I replaced the mode door actuator because mine defaulted on defrost. I would attempt to do the recalibration and it would just keep cycling between defrost, foot, face. Took it to the dealer and they could use the Tech 2 to get it to actuate as commanded through the computer. Suggested I purchase a new control unit. I went the rockauto route and got a new unit. Still same issue. Took it back tot he dealer and they said it had a internal fault to the new head unit. Sent it back to rockauto and the replaced it. Hooked up the new one and I still have the same problem. Got my hands on a autel maxisys reader and it shows two faults for heating and air conditioning. GM DTC B3761 & B0248. These read Airflow control 3 feedback circuit. I purchased another mode door from the dealer this time and the mode door is still not working as it should. The blower and temp select work fine. When I look at real time data it shows no min or max setting for the mode door. I'm trying to figure out where to go next. Two control panels and two mode door actuators.

 

[swathdiver]

I replaced the mode door actuator because mine defaulted on defrost. I would attempt to do the recalibration and it would just keep cycling between defrost, foot, face. Took it to the dealer and they could use the Tech 2 to get it to actuate as commanded through the computer. Suggested I purchase a new control unit. I went the rockauto route and got a new unit. Still same issue. Took it back tot he dealer and they said it had a internal fault to the new head unit. Sent it back to rockauto and the replaced it. Hooked up the new one and I still have the same problem. Got my hands on a autel maxisys reader and it shows two faults for heating and air conditioning. GM DTC B3761 & B0248. These read Airflow control 3 feedback circuit. I purchased another mode door from the dealer this time and the mode door is still not working as it should. The blower and temp select work fine. When I look at real time data it shows no min or max setting for the mode door. I'm trying to figure out where to go next. Two control panels and two mode door actuators.

Joe, could the actual door be stuck or broken? Have you been in there to check them?

 

[smiggs]

I was able to move the doors while I was installing the new actuator. They operate when the mode door is “hunting” from defrost, face, foot.

 

[johnnyCZ]

Hi there, were you able to fix the issue? I have exactly the same behavior on my '02 Avalanche. Also replaced actuator twice, and head unit once to no avail. Seems like it's some wiring issue, but initial tests for the wires continuity didn't show any issue.

I also read one TSB which tells there may be a problem in the junction connector on the right side of instrument panel (under the cover).

 

[JonnyTahoe]

Hi there, were you able to fix the issue? I have exactly the same behavior on my '02 Avalanche. Also replaced actuator twice, and head unit once to no avail. Seems like it's some wiring issue, but initial tests for the wires continuity didn't show any issue.

I also read one TSB which tells there may be a problem in the junction connector on the right side of instrument panel (under the cover).

Having that issue with my 00 Yukon. Bought Brand new AC Delco Mode Actuator P/N; 52473356 moved about a half turn then stopped. Swapped my spare actuator from my Tahoe into the Yukon no movement at all swapped it back into the tahoe now it won't work at all. New Delco actuator wont work in the Tahoe either. Seems the Yukon is burning out these Actuators. No clue what to do worked fine for 20 years now this. Thanks for your info I have had it with this for now.

 

[George B]

Having that issue with my 00 Yukon. Bought Brand new AC Delco Mode Actuator P/N; 52473356 moved about a half turn then stopped. Swapped my spare actuator from my Tahoe into the Yukon no movement at all swapped it back into the tahoe now it won't work at all. New Delco actuator wont work in the Tahoe either. Seems the Yukon is burning out these Actuators. No clue what to do worked fine for 20 years now this. Thanks for your info I have had it with this for now.

Do you have a scanner like a tech2 to view it with?

 

[JonnyTahoe]

Do you have a scanner like a tech2 to view it with?

No scanner never needed one. First time I ever had anything like this happen other than a few Blower Modules.

 

[JonnyTahoe]

Joe, could the actual door be stuck or broken? Have you been in there to check them?

I'm having the exact same problem.

 

[Fless]

No scanner never needed one. First time I ever had anything like this happen other than a few Blower Modules.

You could use one now.

 

[George B]

You could use one now.

This^^^
I threw parts at our Envoy until I had a Tech2. It's fixed now.

 

[JonnyTahoe]

You could use one now.

Thanks for the info Steve.

 

[JonnyTahoe]

This^^^
I threw parts at our Envoy until I had a Tech2. It's fixed now.

Thanks George. I am fortunate I have my one owner Tahoe with a bad Trans for a parts truck for my Yukon. It has saved me on parts a few times.

 

[JonnyTahoe]

You could use one now.

Update. I watched a YouTube vid with GM Techs using a 9 volt battery and wires to bring the actuator back into the proper range. I tested my new ac delco mode actuator before installing it and it went too far and would not work after that. The battery method did not work for me so I took the cover off the actuator and manually brought it back into range by turning the worm gear with my finger for about five minutes. After that the battery worked and the actuator started working like the techs demonstrated NO Tech 2 needed. My new Delco actuator had two white dots in the center of the range so I backed it back up to that spot. After I installed it I turned the key on and the actuator went through the entire range and returned back to the middle. I did not disconnect the battery or anything just turned the key on and it did the Recalibration all by itself and works great.

 

[George B]

Update. I watched a YouTube vid with GM Techs using a 9 volt battery and wires to bring the actuator back into the proper range. I tested my new ac delco mode actuator before installing it and it went too far and would not work after that. The battery method did not work for me so I took the cover off the actuator and manually brought it back into range by turning the worm gear with my finger for about five minutes. After that the battery worked and the actuator started working like the techs demonstrated NO Tech 2 needed. My new Delco actuator had two white dots in the center of the range so I backed it back up to that spot. After I installed it I turned the key on and the actuator went through the entire range and returned back to the middle. I did not disconnect the battery or anything just turned the key on and it did the Recalibration all by itself and works great.

Good news.

 

[DorothysTahoe]

This^^^
I threw parts at our Envoy until I had a Tech2. It's fixed now.

I've been throwing parts at my Wife's TAHOE CJ2 HVAC for a couple years now, multiple control heads, computer modules, and actuators. Where do I get a Tech 2 with all the software and whatnot. Is there a suitable sub that's cheaper than the Tech 2?

 

[George B]

I've been throwing parts at my Wife's TAHOE CJ2 HVAC for a couple years now, multiple control heads, computer modules, and actuators. Where do I get a Tech 2 with all the software and whatnot. Is there a suitable sub that's cheaper than the Tech 2?

Chinacardiags for a tech2
Lots of info here:

Tech 2 Purchase

Time to buy a Tech 2 ..I see a ton of threads when I do a search units clones vs. originals ETC... Where is the best place to purchase? Are there accessories I should be looking at in addition to the unit? Is it even possible to buy a non-clone unit? TIA

www.tahoeyukonforum.com

You can look into a VCXnano too.

 

[MassHoe04]

I've been throwing parts at my Wife's TAHOE CJ2 HVAC for a couple years now, multiple control heads, computer modules, and actuators. Where do I get a Tech 2 with all the software and whatnot. Is there a suitable sub that's cheaper than the Tech 2?

when I got my Tech 2 clone from Chinacardiags.com, it was just about $300 shipped. That was a fair price, but I see they have come down a bit more. Even better!

Things to consider in the decision:
Keeping any GM vehicle from this vintage, a Tech 2 is worth way more than $300.

While good bi-directional scan tools will allow you to see what modules and components are doing and able to make motors and things turn on and off to see what is working or not, the Tech 2 has a number of tests and diagnostic tools not included in other tools.

Also... The Field Service Manual (FSM) is specifically written for use with a Tech 2. The FSM has diagnostic tables for every function and the instructions on what to do and what you should see is geared for the Tech 2 menus.

Can you use the detailed instructions in the FSM with another bi-directional tool? Sure.

But since the FSM is for the Tech 2 and the Tech 2 has other built-in features specific to these vehicles... A Tech 2 could make diagnosis go faster for you.

If you have other non-GM vehicles of different ages, then another tool might make sense.

If older GMs are what you are going to have long-term, then a Tech 2 might just make diagnosis and repairs faster and a little easier with some of the built-in features.