Stereo wiring/auto climate control
Thread Starter
Instructor
Joined: Dec 2007
Posts: 197
Likes: 1
From: Pennsylvania
Stereo wiring/auto climate control
I haven't really gotten any response in the audio section, so maybe someone who hangs out here can give me some info?
I'm putting an after market stereo in a 89 coupe with Bose option. It has the automatic climate control.
There is an output wire from the original stereo, gray/white and shielded. The wiring diagram shows it to be "display dimming output" to "c68 heating and a/c control."
My new HU has no provisions for dimming control.
Is it possible to connect this wire (from stereo to hvac controller) to the gray signal wire going to the stereo?
Is that necessary? The HVAC controller shows the grey wire input pin D14, but also shows the input from the stereo (gray/white) in pin D15.
I have not been able to find any information in searches other than the HVAC controller may be screwed up until you put your Bose stereo back in. I just want the A/C heater controller to work ok with a new headunit.
I'm putting an after market stereo in a 89 coupe with Bose option. It has the automatic climate control.
There is an output wire from the original stereo, gray/white and shielded. The wiring diagram shows it to be "display dimming output" to "c68 heating and a/c control."
My new HU has no provisions for dimming control.
Is it possible to connect this wire (from stereo to hvac controller) to the gray signal wire going to the stereo?
Is that necessary? The HVAC controller shows the grey wire input pin D14, but also shows the input from the stereo (gray/white) in pin D15.
I have not been able to find any information in searches other than the HVAC controller may be screwed up until you put your Bose stereo back in. I just want the A/C heater controller to work ok with a new headunit.
Drifting
Joined: Oct 2006
Posts: 1,554
Likes: 13
From: Romeoville IL
I would try to wire it up without anything extra and see how it all behaves, then dive deeper into the wiring.
Mine's a 90, so the wiring is different. But if memory serves the grey/white wire was the dimmer input to the head unit and didn't interact with the HVAC, but my dash style is much different than yours.
If you do have issues without looping any circuits. You could try to see what the signal output on the grey/white wire is with the Bose in place before you wire it in.
I know there were some issues with the earlier dash and HVAC with aftermarket stereo, but I haven't messed with it or looked for more info.
There is probably a lot of rambling in this lost...
Mine's a 90, so the wiring is different. But if memory serves the grey/white wire was the dimmer input to the head unit and didn't interact with the HVAC, but my dash style is much different than yours.
If you do have issues without looping any circuits. You could try to see what the signal output on the grey/white wire is with the Bose in place before you wire it in.
I know there were some issues with the earlier dash and HVAC with aftermarket stereo, but I haven't messed with it or looked for more info.
There is probably a lot of rambling in this lost...
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
The Grey wire comes from the headlight dimmer switch. It's used to control the brightness of the backlighting for the interior lights and backlighting brightness for the HVAC control head and radio.
When the headlight switch is in head or park, a 12 volt input signal called Lights On is applied to the Bose or Non Bose factory radio. A Digital Dim Signal is generated to dim the Radio and HVAC display (Gray/White wire).
Because you no longer have a radio that can generate this signal. The HVAC display will stay at a fixed brightness. Other than that, the HVAC control head will still function properly.
When the headlight switch is in head or park, a 12 volt input signal called Lights On is applied to the Bose or Non Bose factory radio. A Digital Dim Signal is generated to dim the Radio and HVAC display (Gray/White wire).
Because you no longer have a radio that can generate this signal. The HVAC display will stay at a fixed brightness. Other than that, the HVAC control head will still function properly.
Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
The Grey wire comes from the headlight dimmer switch. It's used to control the brightness of the backlighting for the interior lights and backlighting brightness for the HVAC control head and radio.
When the headlight switch is in head or park, a 12 volt input signal called Lights On is applied to the Bose or Non Bose factory radio. A Digital Dim Signal is generated to dim the Radio and HVAC display (Gray/White wire).
Because you no longer have a radio that can generate this signal. The HVAC display will stay at a fixed brightness. Other than that, the HVAC control head will still function properly.
When the headlight switch is in head or park, a 12 volt input signal called Lights On is applied to the Bose or Non Bose factory radio. A Digital Dim Signal is generated to dim the Radio and HVAC display (Gray/White wire).
Because you no longer have a radio that can generate this signal. The HVAC display will stay at a fixed brightness. Other than that, the HVAC control head will still function properly.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 197
Likes: 1
From: Pennsylvania
Wiring diagram says "display dim signal" from the gray/white wire. the gray wire is interior lights.
My best guess is the temp display will not dim with it open, just full bright all the time.
I just don't want to tear this thing apart again..
My best guess is the temp display will not dim with it open, just full bright all the time.
I just don't want to tear this thing apart again..
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
I hope you are right, since my new aftermarket stereo was installed by Best-Buy the heater/ac control will not work properly, heat when warm outside and a/c in the winter. I am in the process of reinstalling the stereo and connecting the correct wires based on the FSM diagram.
You should disconnect the negative battery terminal for a couple of seconds then reconnect it.
Turn the ignition on and you should hear the blend door motor moving from one extreme to the other then position the door to a know position. Takes about 30 seconds then the blower motor turns on.
From your description the blend door position information is messed up.
Also make sure the electrical connector on the back of the HVAC control head is secure.
Last edited by Hooked on Vettes; Mar 18, 2008 at 01:56 AM.
