I have been informed that the HVAC Control Head needs to be replaced. Symptom: in heat mode adjusting the control **** only moves the temp 2 degrees around 70 degrees. Apparently, the HVAC Control head is not sending out the pulses to the air door motors. (Confirmed by the scan tool test).

Question. . .Do I have to buy this part from the dealer or are there other places to get these new or rebuilt?

Any help or suggestions aprecciated

C5, 2000, Convertible

 

A long time ago and on a different car, a dealer wanted about $500 to replace an electronic head unit. I wasn't willing to spend that much, so I removed, took off the covers, and blew it out with a can of compressed air (like you use on computers).
The fixed the non-responsive controls, and it worked fine for the rest of the life of the car (another 4 years, I think).

Guess dust/dirt infiltrated the unit and blocked some of the contacts, and the air blast cleared it out.


About 1.5 years ago, I had the (C5) HVAC head unit GMPP replaced due to a faded out display - I believe the dealer told me it was a 300$ part, plus labor.


I think 74 is the highest the controller will go, be it driver or passenger, adn the lowest is about 62. Does yours work correctly at the lower end of the scale?

AJ
01 NBM Coupe
MN6
R8C

 

AJ:

Thanks for the quick response.

My unit's display is fine but the temp values only hover around 70 degrees +/- 1 degree. I haven't been able to get below that at all.

Replacement for the unit is about $400 from Chevy dealer (plus installation). I was hoping for a place to pick up a discounted unit even a rebuilt or slavage.

I will try removing it and checking it out. I do have some electornic skills and maybe there is something obvious.

 

You can purchase the control module from Fred Beans Parts for $194.00. My local dealer wanted $385.00 for the same unit.

 

I will call them.

 

Before you invest in a new unit, I would try this.

- First, blow the unit free of dust per a previous post.

- Second, with a good magnifying glass or better yet, 2x or 3x spectacles from a Walgreens, examine all solder joints of all the internal electrical connections.

I have never had a HVAC control unit apart, but my experience with electronics in-general is that all too often, the trouble is a cracked solder joint. On vehicles, usually solder joints fracture at large or heavy components, and also at connector pins. They tend to resonate from the car's motion and engine vibration, causing the solder joint to crack and cause the unit to malfunction, often intermittently.

I have repaired home stereo equipment, car stereos, TVs, toaster ovens, coffee makers, hair dryers, etc. all from failed solder joints. In stationary appliances around the house, the cracks usually occur from the heating and cooling from normal use.


Just re-solder any suspicious looking solder joint with a soldering iron and some flux. You can buy flux in a tiny toothpaste tube at Radioshack real cheap. The flux makes the molten solder form properly. It makes the difference between a good solder joint and a bad one.


You'll have a better than a 50% chance of fixing it, and all it cost was a little of your time.

There was and maybe still is a guy on ebay who will repair your HVAC unit. Maybe he knows what joints fracture, and makes a 2 minute repair and charges you good money for it.

 

The email address of the guy who fixes them is (was??) caferacer1@comcast.net
He charged $50 to fix the display which is quite reasonable. I don't know if he can fix your problem.

I bought a new one from Fred Beans myself.