2005 Tahoe B0229 - both front AC vents hot, rear vents cold

[tennfire]

2005 Tahoe LT
Automatic climate control for left and right front plus rear air.
Code - B0229 recirculate actuator out of range

Started this weekend, with vehicle running and both front temperatures setting on 68 and outside air close to 90. Both interior vents have warm air (not cold but not straight heat - but about the temperature of the outside air +/-). The rear air, including the ceiling vents about the back seat, is cold.

I pulled the fuse under the hood with the motor off and left out for about 2 minutes. When I plugged it back in and turned on the vehicle, temp on AC control showed 74 and I let it run at that setting for about 5 minutes then shut off for 20-25 seconds. Then restarted. Still warm air up front and cold in the rear. Changing temperature to max heat, I got more heat. Changing temperature to max cool, I got approximately ambient outdoor temperature (mid 80s).

Although the recirculator should, if I understand, switch from outdoor air input to in-cabin air recirculate, would that explain lack of cooling on the front dash?

The fact that temperatures are same on both front vents when set to max cool, it does not seem that it would be the left or right actuators unless both failed at the same time.

Is there a temperature blend door that works in conjunction with the left and right temperature controls and actuators?

 

[tennfire]

Update: I pulled the front vents on either side of the airbag. On the left vent you can see the upper blend door actuator and can watch it move as I change the temperature. I pulled the cover under the dash and observed the actuator above the passenger floorboard near the transmission hump and it is moving as well. If i look through the air vent on the right hand side of the airbag, i can see what appears to be the recirculation door but it is not moving when the recirc button is pressed.

I also checked the pressures on the AC charge and given the ambient temp they seemed appropriate which is somewhat consistent with good cold air from rear HVAC and the low pressure side of the AC line serving the front AC.

But the front air, although it seems perhaps a few degrees cooler than ambient is probably 20-30 degrees higher than the rear AC.

Would an inoperable recirc actuator impact the temperature on the front vents? On my Silverado (a 2000 model), the recirc perhaps reduces the vent temps a few degrees but not 20-30 degrees.

What else to check?

 

[Smooth]

I’m having a similar issue but I get no air flow at all through the front vents and full air flow in the rear

 

[retiredsparky]

The front HVAC control module (part of the display) has sole control over the front air temperature and fan speed. It has no effect on the rear unit.

The code certainly points toward either the controller or the circulation actuator. It is possible that the error code indicates that the actuator has failed. This error may confuse the controller and cause it to not function correctly.

The other possible cause is that the controller has failed, and happens to generate the indicated code.

I suggest replacing the actuator first, since this is less costly and may solve the problem. If the problem persists, after going through the reset steps, replace the controller with a reman unit (no new ones are available).

Unfortunately, these controllers are not very reliable, even after being renovated.

Good luck!