Blend doors

[Twithers]

I have a 2004 Tahoe with rear A/C controls. Currently, I have no heat from either the front or rear vents. I've read that the blend door could be the problem. Do the rear vents work off the same blend door for temp control? If not, is it likely that both blend doors failed in the cold position, or could thee be another problem?

I did have a leak in one of the heater hoses in the engine bay, so I had to fix that and then fill up the coolant reservoir a couple times to get the air out. Is there any sort of special bled procedure to get any trapped air out of the heater hoses, especially for the rear system?

I just find it coincidental that multiple blend doors would all fail in cold mode together, but I don't really know the systems very well.

Thanks.

 

[Joseph Garcia]

@swathdiver

 

[Fless]

The blend doors for front and rear are separate. Is your front HVAC head automatic (with temp numbers) or manual with the two sliders?

The auto HVAC has sensors in some of the ducts. I'm not saying that's what's wrong, but it would be incredibly helpful to check this out with a Tech 2 bidirectional scanner.

 

[swathdiver]

I have a 2004 Tahoe with rear A/C controls. Currently, I have no heat from either the front or rear vents. I've read that the blend door could be the problem. Do the rear vents work off the same blend door for temp control? If not, is it likely that both blend doors failed in the cold position, or could thee be another problem?

I did have a leak in one of the heater hoses in the engine bay, so I had to fix that and then fill up the coolant reservoir a couple times to get the air out. Is there any sort of special bled procedure to get any trapped air out of the heater hoses, especially for the rear system?

I just find it coincidental that multiple blend doors would all fail in cold mode together, but I don't really know the systems very well.

Thanks.

There are 4 actuators up front and 1 or 2 in the back. All of mine have thrown codes at one time or another and then kept on working and cleared themselves for a time only to act up again some time later. Your controller might also be on the brink or need recalibrating. Much to guess on which can get expensive if you fire the parts cannon at it. Who do you know with a Tech-2 or similar scan tool that can read BCM codes?

 

[Twithers]

I replaced the climate control module because the temp dials were failing. The numbers would just jump up and down no matter how you turn it. It didn't have any effect on the lack of heat. I put my scanner on it and got these 2 codes from the HVAC system:

B0414-13 Temp control 1 feedback circuit range/performance.

B0424-13 Temp control 2 feedback circuit range/performance.

 

[Twithers]

Bit of an update/wrapup.

I found the driver's and passenger's blend doors unplugged. I plugged them back in and cycled several times from full hot to full cold and everything worked fine. I don't know why someone unplugged them, but if I had to guess, either they were failing intermittently (and will again), or the climate control module was actually the problem but they didn't know it and decided to get it to full cold and leave it there. I already replaced the climate control module because both temp control potentiometers would jump around all over the place when you turned the knob.

The rear blend door was still plugged in and I couldn't get it to work. But one blend door failing makes much more sense than all 3.