HVAC Nightmares!!!

[StealthTahoe]

I have an 07 LT Tahoe with the digital dual zone HVAC system with digital rear air as well. I have a couple things going on that I cant figure out.
1st- My front HVAC does not blow warm or hot air until I go to 90* then it blows hot like it should. Anything under 90* blows cool air or cold if the temp is set low. The "Auto" option doesn't seem to be working either. This is the same for both driver and passenger sides.

2nd- My rear air started off intermittently working and not working. Now it doesn't turn on at all. The display turns on at the rear panel but no air is blowing at all.

I have googled and searched without much luck or guidance. Most issues I found are older vehicles and not the same symptoms I have.

Now for what I have tried based off of internet searches.
Front- Pulled fuses for about an hour, also disconnected the battery on a subsequent attempt, to allow the system to rest. I let it do it's start up sequence every time I tried this, but nothing worked. I have no clue what to do now. ****I am not sure if the interior ambient temp sensors are working***

Rear- This really irritates me because it used to work great. I have pulled every component out of the back, blower motor resistor, blower and fan and installed them in the front. They worked fine in the front, but the front didn't work in the back, so I put them back to their original spots. I used a multi meter to check voltage and the PURPLE ( I think its purple, it's the third wire on the resistor connector) has no voltage, this is supposed to be the speed control wire. I traced this wire all the way to the drivers side kick panel and there are no breaks. I disconnected the plug in the kick panel and ran a jumper wire from the front blower motor resistor and the damn thing worked. I could fan speed on the drivers control, and heat and cooling plus head or foot vents on the rear panel.

Is there something else I can try or am I going to have to take it to the dealer for troubleshooting????
Please help!!!

 

[badandyturbo]

Have you checked the air blenders for the drivers and passengers side?

 

[nixxxster]

My 2009 have the same issue sometime. Any input fro be great.

 

[StealthTahoe]

No, I have not checked the blend doors. From what I understand there is one that you basically have to pull the dash apart to get to. I am hoping that is not the issue.

Have you checked the air blenders for the drivers and passengers side?

 

[Brian Wilson]

Blend doors are a known problem. But yours sounds more like the front control might be messed up. Just an educated guess.

 

[StealthTahoe]

SO, I realize it has been a while since my original post, but I have an update from today..... I FIXED THE DAMN A/C!!!!
For the FRONT issues, I dropped the headliner and pulled the aspirator out. At first glance, it was disgusting and covered in dust. I gently cleaned it off with canned air and a dry rag. after cleaning it, I pulled the harness through the hole and hooked the fan back up. to my surprise it worked as soon as I turned the key. At that point I put it all back together and moved to the other HVAC issue.
For the REAR issues, I ended up sitting down with my multi-meter and tracing every wire that I could from back to front. following the wiring diagram in my trusty Haynes manual I was able to narrow it down to the front climate control module due to the lack of voltage changes when I selected different things on the rear controller. At this point I pulled the controller out and proceeded to disassemble it. upon further inspection after I removed the circuit cards I found that the GREEN harness had a burned pin on..... wait for it.... the Dark Green wire that controls the rear blower motor speed. So borrowed a controller, hooked it up, and puled the HVAC fuse under the hood to perform the calibration sequence. after calibrating everything worked on both front and rear systems... needless to say I am extremely happy with myself. Other than a little time here and there I will have fixed my A/C for about $60 on a used controlled from the salvage yard instead of the $75ish an hour the dealer wanted to charge to troubleshoot the A/C with their scanner and then parts and labor.

 

[Rocket Man]

Awesome job. Perseverance paid off!

 

[2011SSVHOE]

Good job. Seventy dollars an hour is cheap around here

 

[Mp619]

SO, I realize it has been a while since my original post, but I have an update from today..... I FIXED THE DAMN A/C!!!!
For the FRONT issues, I dropped the headliner and pulled the aspirator out. At first glance, it was disgusting and covered in dust. I gently cleaned it off with canned air and a dry rag. after cleaning it, I pulled the harness through the hole and hooked the fan back up. to my surprise it worked as soon as I turned the key. At that point I put it all back together and moved to the other HVAC issue.
For the REAR issues, I ended up sitting down with my multi-meter and tracing every wire that I could from back to front. following the wiring diagram in my trusty Haynes manual I was able to narrow it down to the front climate control module due to the lack of voltage changes when I selected different things on the rear controller. At this point I pulled the controller out and proceeded to disassemble it. upon further inspection after I removed the circuit cards I found that the GREEN harness had a burned pin on..... wait for it.... the Dark Green wire that controls the rear blower motor speed. So borrowed a controller, hooked it up, and puled the HVAC fuse under the hood to perform the calibration sequence. after calibrating everything worked on both front and rear systems... needless to say I am extremely happy with myself. Other than a little time here and there I will have fixed my A/C for about $60 on a used controlled from the salvage yard instead of the $75ish an hour the dealer wanted to charge to troubleshoot the A/C with their scanner and then parts and labor.

So basically you replaced the front climate control module? I am having the rear climate control problems and i am hoping this might be the solution, i could just pick up a replacement.

 

[Mp619]

T

SO, I realize it has been a while since my original post, but I have an update from today..... I FIXED THE DAMN A/C!!!!
For the FRONT issues, I dropped the headliner and pulled the aspirator out. At first glance, it was disgusting and covered in dust. I gently cleaned it off with canned air and a dry rag. after cleaning it, I pulled the harness through the hole and hooked the fan back up. to my surprise it worked as soon as I turned the key. At that point I put it all back together and moved to the other HVAC issue.
For the REAR issues, I ended up sitting down with my multi-meter and tracing every wire that I could from back to front. following the wiring diagram in my trusty Haynes manual I was able to narrow it down to the front climate control module due to the lack of voltage changes when I selected different things on the rear controller. At this point I pulled the controller out and proceeded to disassemble it. upon further inspection after I removed the circuit cards I found that the GREEN harness had a burned pin on..... wait for it.... the Dark Green wire that controls the rear blower motor speed. So borrowed a controller, hooked it up, and puled the HVAC fuse under the hood to perform the calibration sequence. after calibrating everything worked on both front and rear systems... needless to say I am extremely happy with myself. Other than a little time here and there I will have fixed my A/C for about $60 on a used controlled from the salvage yard instead of the $75ish an hour the dealer wanted to charge to troubleshoot the A/C with their scanner and then parts and labor.

his is the part i am referring to