Broken blend door B3779-02

[barneyfife68]

2009 GMC Yukon XL SLT 199k
Bought this last winter. Its in great shape but noticed drivers side HVAC controls acting wonky. Noticed the pass side blend motor was unplugged (found out later the passenger side blend motor controls the DRIVER side door/AC) To make a long story short, ended up replacing three blend motors (pass side footwell, passenger side by airbag, drivers side by throttle pedal). No change. Now it's summer. Pass side and rear A/C work great! Drivers side just blows hot outside/engine heat.

Finally got a scanner on it at my dealer. Diagnosis at dealer shows following comments:
"B3779-02 stored. The command actuator is moving to correct position. Remove actuator and manually move left HVAC door. Door is broken internally in case. Need to remove HVAC case and replace door assy"

So...is there an easy bypass for the summer? I have no problem disassembling the entire dash to replace the blend door, just was hoping to wait until a more convenient time. I'll take any advise given! Thanks so much.
Jim in SW Idaho

 

[barneyfife68]

To partially answer my own question:

Anyone have a better solution??? I love Gorilla/duct tape as much as the next person but....

 

[swathdiver]

2009 GMC Yukon XL SLT 199k
Bought this last winter. Its in great shape but noticed drivers side HVAC controls acting wonky. Noticed the pass side blend motor was unplugged (found out later the passenger side blend motor controls the DRIVER side door/AC) To make a long story short, ended up replacing three blend motors (pass side footwell, passenger side by airbag, drivers side by throttle pedal). No change. Now it's summer. Pass side and rear A/C work great! Drivers side just blows hot outside/engine heat.

Finally got a scanner on it at my dealer. Diagnosis at dealer shows following comments:
"B3779-02 stored. The command actuator is moving to correct position. Remove actuator and manually move left HVAC door. Door is broken internally in case. Need to remove HVAC case and replace door assy"

So...is there an easy bypass for the summer? I have no problem disassembling the entire dash to replace the blend door, just was hoping to wait until a more convenient time. I'll take any advise given! Thanks so much.
Jim in SW Idaho

There are three actuators on the passenger side of the dash. Two up top and one down below near the transmission hump. This latter one controls the driver's side temperature.

In the driver's footwell is the Mode Actuator which is what that code is for. That one controls where the air goes in the system, feet, vents, dash, etc.

I don't know of a temporary or bush fix. It is fairly easy to access if you are nimble enough and can verify that the door is indeed broken and not mistaken or dishonest.