Hello Community!

This is a help as well as an FYI...

I have a 2006 Monte Carlo LT, 3.9 liter. I recently removed the Heater/Air Conditioner Control Assembly in the interior and replaced it with a new, AC Delco/GM assembly, AC Delco #15-74130/GM #20972894

Here is the full description from Tonkin Online Parts (GM parts website):

CONTROL. HEATER AND AIR CONDITIONING (A/C) CONTROL
CONTROL,HTR & A/C(ACDelco #15-74130). CONNECTOR-CONTROL, Heater and A/C Control. For: W A/C FRT MAN/AUX CONTROL(CJ3),(EXC ST HTR(KA1) (2006-2007) (2006 - 2007). Required: 01

I have confirmed the new Heater/Air Conditioner Control Assembly with a number of other websites catering to GM/Chevy parts. GM, as with other manufacturers, have a tendency to add part numbers that are compatible but have no physical difference. It's mostly an internal update to the inside parts or materials or design change. The connectors are physically the same as the unit I replaced it with.

Having said that, after I replaced the old unit with the new unit, I noticed that the outside temperature on the DIC (Driver Information Center) now reads: "---" instead of the outside temperature. I also heard static/frequency interference when I turn on the Rear Window Defrost/Defogger. This is the second time that I replaced the module with a new part. The same experience has occurred. When I plug in the old part, everything works again and no speaker/radio static. (update: In this case, the static issue has to be the result of a change within the system itself (electrical, physical, etc...) as oppose to the old one, which results in a change to the part number. That's an FYI! Having tested two new units and getting the same positive results, it cannot be coinscidence that it is the rear defrost ground connection.) My radio is "GM new" and has been unlocked/programmed to the car.

The feature within the factory remote start (which I have) turns on the Heater/AC Control Assembly to adjust for the ambient temperature in the car. (The blower does not come on) This happens with the new modules.

Yes, the negative battery terminal was disconnected before removal, so the airbag does not accidentally deploy.

The 2006-2011 Monte Carlo/Impala Haynes Manual quotes: "If the heater/air conditioner control assembly is replaced, a special scan tool is required to program the replacement unit." I had the Chevy dealer quote me $125. That's a bit steep. I tried a local garage to no avail. Does it have to be reprogrammed with the GM Tech2 Scan Tool only? Dealer only fix? Body Control Module, Electrical Control Module or Powertrain Control Module?

Hope to hear from some members soon.
Thanks MC Community, for your help.

 

Welcome to the MCF

I hope that one of our expert member's with tech knowledge can help you with your problem.

From your post it sounds like you have advanced knowledge on working on your Monte.

$125 doesn't seem outrageous to me as a quote from a dealer to resolve your issue. A hand held Tech 2 sells from $3o9 +

2014 Newest For GM Tech2 Diagnostic Scanner For GM/SAAB/OPEL/SUZUKI/ISUZU/Holden
================================================== ========
OTC 3648
GM Tech 2 Scan Tool Basic Kit

Product Code: OTC-3648
Regular Price: $7,369.44
Sale Price: $4,249.96

https://www.americastoolwarehouse.co...FQoEaQodpocAyw
============================

Good Luck on getting your issue fixed.....

 

Update: I had the HVAC unit reflashed/relearned. $95. Fixed everything but the static. The static interference while the radio is on and the rear defrost is on at the same time it is the FM frquency only that acquires the static. The AM frequency is just fine. The FM frequency/antennae reception was resolved after repairing small cracks/breaks in the rear view defroster grid.

 

I don't know about the 06-07 Monte, but in the 00-05 Monte, behind the upper rear driver side trim panel is a small black box. THis box is used to manage the defroster and window antenna connections to the lines on the rear window. I believe the shop book says for your condition (static on the radio when the rear defroster is on) that box is the culprit.

I'm assuming it's the same for the '06-07 Monte. And as I recall in the '00-05, there were two different part numbers. I have never changed one out, but I don't believe it would be too tough.

I hope that helps.