01 Suburban rear heat/ac

[SpareParts]

Mine works but not properly and i can't seem to find a answer searching.
It will blow cold air always unless i turn the temp to max hot then it switches to blowing hot air. It will not regulate the temp warm air like the front does.
It is the same when using the front controls for the rear or the rear controls.
Since it will switch from cold to hot i assume the blend door actuator is working.
I did read something about a IR sensor and i do have one mounted in the rear control panel. Guessing that might be the problem?
Any ideas on what to check?

 

[Doubeleive]

Mine works but not properly and i can't seem to find a answer searching.
It will blow cold air always unless i turn the temp to max hot then it switches to blowing hot air. It will not regulate the temp warm air like the front does.
It is the same when using the front controls for the rear or the rear controls.
Since it will switch from cold to hot i assume the blend door actuator is working.
I did read something about a IR sensor and i do have one mounted in the rear control panel. Guessing that might be the problem?
Any ideas on what to check?

I could be wrong but I don't think the 01's have a sensor, but if it does you can check it with a ohm meter and a hair dryer, probe the sensor legs with the meter and apply hot air to see if it changes ohm's. it will be mounted in the duct housing forward of the hot/cold actuator and rear of up/down Y.
since you get the same results from either control I would probably rule the controls out and concentrate on either the rear main control or the actuator.
there are plenty of these in the junkyard I would go out and grab a actuator from a yard and try swapping it out first. the one you want is the rear one closest to the blower motor
if the actuator is bad it may not like the full position command and decide to just flip the other way on it's own.
**note that you may need to get a actuator out of a 00-02, they made changes in the electronics in 03 and around 04 they started with the digital controls so the actuator *could* be different. but might not be.

 

[mattbta]

Get a scan tool that can access body codes - there might be some historical ones stored. On my 2004 I have B0434 which is a temp control module for rear climate. This wouldn’t show using a cheap OBD dongle.

Not saying above code is your problem, just that higher level scan tools may provide more information.

 

[Fless]

Get a scan tool that can access body codes - there might be some historical ones stored. On my 2004 I have B0434 which is a temp control module for rear climate. This wouldn’t show using a cheap OBD dongle.

Not saying above code is your problem, just that higher level scan tools may provide more information.

^^ This is definitely a great idea. In addition to that, GM issued updated calibrations (firmware) for at least the front automatic controls. If you know someone who can program modules or can even just check to see what calibrations are being used for both controls, you could have them updated if newer ones are available.

 

[SpareParts]

Was at the wrecking yard and found the only rear control module they had and it reads in C instead of F. Not a real problem if it works.
Took the old module out and plugged in the wrecking yard one.
Rear heat now works perfect. Pretty sure it was something wrong with the IR sensor.

 

[SpareParts]

Get a scan tool that can access body codes - there might be some historical ones stored. On my 2004 I have B0434 which is a temp control module for rear climate. This wouldn’t show using a cheap OBD dongle.

Not saying above code is your problem, just that higher level scan tools may provide more information.

I do have a Snap on Solus pro that i believe will read up to 2014. Works fine on the wives 2013 Avalanche anyway.

 

[Doubeleive]

Was at the wrecking yard and found the only rear control module they had and it reads in C instead of F. Not a real problem if it works.
Took the old module out and plugged in the wrecking yard one.
Rear heat now works perfect. Pretty sure it was something wrong with the IR sensor.View attachment 413967

huh, had no idea there was a sensor there, nor that there was a "auto" option for that year. but that would make sense
on the newer trucks all the sensors are in the duct work or in the headliner

 

[Fless]

You may be able to swap the faceplates or the body of the control. Lots of times they come apart fairly easily, especially to fix backlighting.

 

[SpareParts]

You may be able to swap the faceplates or the body of the control. Lots of times they come apart fairly easily, especially to fix backlighting.

Yup thats the plan.