Rear ac not working

[Dahoe06]

I have a 2006 Tahoe z71 and the front air works fine but no air is coming out of the rear vents, no heat or AC. Is there a mode door or something I need to replace or is there a separate motor for the rear? Thanks!

 

[79jasper]

Rear is separate. There's some youtube videos out there. Start simple with fuses.

Sent from my SM-N960U using Tapatalk

 

[Joseph Garcia]

I believe that a member posted an entire schematic of the rear heater/AC assembly within the past week or so. Perhaps, someone here remembers specifically which post that was, and it may be helpful in this case.

If there is no air flow in either heat or AC, the first thing that I would check would be to see if the blower motor is turning, as I believe that there is a separate blower motor for the rear. I think that you would hear it in the rear of the truck, if it were turning.

 

[Doubeleive]

if you have no air coming out of the rear hot or cold then the blower motor or blower motor resistor may be bad, there is no blend door to completely cut off the air it blends either up to the roof vent or down to the floor vents or mixes hot/cold there is only 2 doors. the rear consist's of a control module, blower resistor, blower, up/down actuator, hot/cold actuator.

 

[David Staines]

Would the blower motor resistor being bad also prevent the actuators from working?

 

[PNWYukon]

 

[alex s]

Following this. I have the same problem.

 

[David Staines]

I just spend the last two days absorbing everything youtube had to offer on this subject.

1) Check the fuse
2) Check for power at the input to the resistor

If those two are good, change the resistor

Other things I'd check to make sure:

1) Is your front controller set to "off"?
2) Check you have power on across the white connector behind the emergency brake panel (orange wire)

I'm not sure, but one of these two fixed my fan not coming on.

After that, I found that I was only blowing hot air. When I checked the hot/cold actuator, I found it wasn't moving correctly. The previous owner had replaced this already. After much more internet searching, I decided to disconnect the ground on the battery for a minute (2001 Tahoe. 2003 and up you can simply remove the controller fuse for a minute). I reconnected the battery and turned the ignition to the on position without staring (two positions). I went in back and watched both the up/down and hot/cold actuators calibrate and home. I waited a few more minutes and started the vehicle. The hot/cold actuator now works and I get cool air. I'll have to wait for the day to heat up a bit and see how well the AC actually works, but at least now I know I'm blowing across the AC coil.

 

[David Staines]

Now... I'm blowing kinda cold up front and not cold in back. I also developed a ticking noise that seemed to be coming from the water pump or compressor. I went in and turned off the AC with the engine running and the ticking noise went away. I'm thinking a new compressor, orifice tube and rear expansion valve.