2012 Tahoe/ Roof AC vents not working

[Mkino]

Roof vents are not blowing at all, but the vent near the passenger side rear tire blows cold air just fine.

Any ideas? Thanks in advance!

 

[Mkino]

2012 Tahoe LTZ

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me in this area will chime in.

Is this issue something new that suddenly popped up? Did you recently perform and maintenance or mods on the truck that could even be remotely associated with this issue?

Do you have a Tech 2 or similar bi-directional scanner, as it would be very helpful in providing information on the performance (or lack thereof) of elements of the HVAC system.

@swathdiver

 

[j91z28d1]

yeah, sounds like it's blowing cold where we t normally blows heat. have you adjusting it?

 

[swathdiver]

Roof vents are not blowing at all, but the vent near the passenger side rear tire blows cold air just fine.

Any ideas? Thanks in advance!

That's probably the auxiliary mode actuator not doing its job anymore. If you can get a bi-directional scan tool on it, Code B3782 would probably be there to confirm the problem.

The rear AC has two actuators, one to control where the air goes and one for the temperature. They use the same actuator, ACDelco 15-72972 or GM OE 89018375. Both numbers on the same box. Aftermarket units do not last. Some folks have success just replacing the actuator without a relearn. Others have had success doing a manual relearn. I've always had to use my Tech-2 (bi-directional scan tool) for a successful relearn.

 

[Mkino]

Thanks swathdiver, that makes sense. I'm a decent mechanic, but I think this might be above my pay grade as I've never heard of a bi-directional scan tool...

What I'd like to do is permanently leave the duct open to the roof vents whenever the rear ac is turned on, i.e. remove the diverter? Probably a really bad idea but I'm throwing it out there...