HVAC Control Head

[smetzler]

I recently purchased a 2003 Pontiac Grand Prix GT. I took it into service and they indicated the HVAC Control Head might be bad. This may be causing the lights to go off / on and possibly when I switch modes of where the air comes out that it does not work.

As a suggestion, they suggested I could try to find this head at a junk yard and do it myself, but have no idea how to start. Basically my main concern is how do I get the old HVAC Control Head off. With cars (at least with me), its not apparent of how to undo stuff (e.g., screws that unscrew to take it apart, fix it and put it back together).

Any suggestions / guidance on above would be greatly appreciated.

Shawn

[BNaylor]

Can you be more specific on your problem? What blower speed positions are not working, if any? Before yanking the control head and possibly wasting money there are other possibilities: blower motor, blower motor resistor/control module, and in a worse case scenario a defective ignition switch assembly could cause the problem especially since you mentioned affecting the headlights.

Do you have a manual HVAC system or digital climate controls?

[smetzler]

Thanks for the reply.

I have the dual temperature control (not digital)

When I switch from Defrost/Floor to Floor, there is still quite a bit of air coming out of the Defrost. The speeds all seem to be working. Its the flow of the air that I seem to be having trouble with.

With the light (not the headlights - sorry about that), it is the light that is above the A/C button that notes if the A/C is on or off. It flickers off/on when the A/C is on.

I also have a separate problem with the radio where the time and station LCD displays sporadically. Everything works, its just the LCD doesn't always display the time and station. Its very sporadic when it works.

Shawn

[waffle101]

I have a 2001 gtp se with the same problem , but my fan only works on number 5 , 1-4 has nothing , can you tell me what needs to be fixed or looked at ? Thanks !

[BNaylor]

Originally Posted by smetzler

Thanks for the reply.

I have the dual temperature control (not digital)

When I switch from Defrost/Floor to Floor, there is still quite a bit of air coming out of the Defrost. The speeds all seem to be working. Its the flow of the air that I seem to be having trouble with.

With the light (not the headlights - sorry about that), it is the light that is above the A/C button that notes if the A/C is on or off. It flickers off/on when the A/C is on.

I also have a separate problem with the radio where the time and station LCD displays sporadically. Everything works, its just the LCD doesn't always display the time and station. Its very sporadic when it works.

Shawn

Thanks for the explanation. The head unit controls door actuators both vacuum and electrical so it will need to be removed for troubleshooting. Probably a good idea to make sure the electrical connectors on the head unit and radio are tight. The original diagnosis was probably correct. Also with it removed you can check the vaccum lines to certain actuators. If you remove the glovebox door you should be able to see the defrost actuator to the left.

To get to everything you'll need the remove the plastic dash bezel just like getting to remove the radio. The radio with the LCD problem sounds like an internal electronic problem (LCD driver). There are backlight lamps but I don't think that's the problem.

[smetzler]

Thanks for the help. Greatly appreciate it. Only have one question.

I've never done this before. You indicated what to remove and what to do, but my problem is I don't know how to do this. For example, I just rebuilt parts of our ice maker among other things. I could see where the screws were and how to take it apart and put it back together. With a car, that is where I am stumped. At least for me its not something that I can easily see of how to get started (e.g., where are the screws to take out the HVAC control head) so I can take out the unit.

I hope I'm explaining myself correctly.

Shawn

[BNaylor]

Checkout link below. It should give you an idea how to go about it.

http://www.carstereohelp.com/stereor...andPrixSt2.htm

[weaselphd]

My problem is similar, i have a 2002 grand prix gt, and the climate control is the non-digital 2 zone set up. again today the first big winter storm, no FAN controls, the dealer has replaced this unit as defective 2 times already, this is the 3rd POS unit. iwas wondering can i just replace it with the digital version i seen a few on ebay and since my warranty is up i will not take it back to the dealer?
i think the model number of the digital is model # 10435239

thanks
Michael

[BNaylor]

Originally Posted by weaselphd

My problem is similar, i have a 2002 grand prix gt, and the climate control is the non-digital 2 zone set up. again today the first big winter storm, no FAN controls, the dealer has replaced this unit as defective 2 times already, this is the 3rd POS unit. iwas wondering can i just replace it with the digital version i seen a few on ebay and since my warranty is up i will not take it back to the dealer?
i think the model number of the digital is model # 10435239

thanks
Michael

I've never heard of a successful conversion from manual to digital but you never know. Other than replacing the head unit, the you'll need the digital system's blower motor. They are not the same and the blower motor resistor is replaced with a blower motor control module. Plus wiring would need modification to connect everything and addition of temperature sensors. The AC controls interface is different including hookups to compressor, vent actuators, temperature actuators and vacuum control.

It sounds like you may need another manual head unit.

[weaselphd]

Originally Posted by bnaylor3400

I've never heard of a successful conversion from manual to digital but you never know. Other than replacing the head unit, the you'll need the digital system's blower motor. They are not the same and the blower motor resistor is replaced with a blower motor control module. Plus wiring would need modification to connect everything and addition of temperature sensors. The AC controls interface is different including hookups to compressor, vent actuators, temperature actuators and vacuum control.

It sounds like you may need another manual head unit.

im glad i asked i think you are right, do you knnow if these fan control switches are just junk or whats the deal i have heard of so many of these going bad. i will order the new manual unit right now.

thanks
Michael

[BNaylor]

Originally Posted by weaselphd

im glad i asked i think you are right, do you knnow if these fan control switches are just junk or whats the deal i have heard of so many of these going bad. i will order the new manual unit right now.

thanks
Michael

The '97 - '99 manual units seemed to be more reliable. From what I understand from 2000 and up GM started having these units manufactured in Mexico at the Delphi plants. Maybe it is a quality control issue. Also with the head unit out it would be a good idea to check the wiring at the electrical connectors and make sure the ground(s) is good. Also inspect the blower motor resistor and blower motor assembly. Good luck!

[weaselphd]

Originally Posted by bnaylor3400

The '97 - '99 manual units seemed to be more reliable. From what I understand from 2000 and up GM started having these units manufactured in Mexico at the Delphi plants. Maybe it is a quality control issue. Also with the head unit out it would be a good idea to check the wiring at the electrical connectors and make sure the ground(s) is good. Also inspect the blower motor resistor and blower motor assembly. Good luck!

is there a way to jumper some wires behind the fan dial to manually get the fan to run so that the car will have heat unntil the new unit arrives?

thanks
Michael

[BNaylor]

Originally Posted by weaselphd

is there a way to jumper some wires behind the fan dial to manually get the fan to run so that the car will have heat unntil the new unit arrives?

thanks
Michael

Are you getting illumination and other controls on the head unit when ignition is in run? Need to be certain the 12v is there. It can be done but not recommended unless you know the blower and resistor are good for sure.

Have you checked fuses: HVAC CTRL, HVAC HI & DIC/HVAC. They will be located in the engine compartment fuse box and passenger side cabin fuse box.

You'll need a GM Grand Prix wiring diagram for reference.

[smetzler]

Thank you for the replies and help.

[weaselphd]

Originally Posted by bnaylor3400

Are you getting illumination and other controls on the head unit when ignition is in run? Need to be certain the 12v is there. It can be done but not recommended unless you know the blower and resistor are good for sure.

Have you checked fuses: HVAC CTRL, HVAC HI & DIC/HVAC. They will be located in the engine compartment fuse box and passenger side cabin fuse box.

You'll need a GM Grand Prix wiring diagram for reference.

agreed yes the lights work, in fact the damn thing started working again. but it is still acting funny... same symptoms last time when the control panel needed replaced, so i have one on the way.

thanks for all your help!
Michael