Air Conditioning Head Unit Switch

[Centrinomw]

Hello, I Have a 1998 Pontiac Grand Prix SE 3800 Sereis 2. I as of now I have a Air Conditioning with Electronic Controls, which is the basic package with all the knobs. I want to upgrade to a Air Conditioning with Automatic and Auxiliary Temperature Control, which is the upgraded system with Automatic Temperature and the driver passenger split. Does anyone know if this will work or If it cannot be upgraded. Any answers would be appreciated. Are the Harnesses the same?
Thank you

[BNaylor]

To upgrade or convert to the automatic climate control system (ACC) GM RPO CJ2 you would need a new dash wiring harness that will support the HVAC system since there are major differences. For hardware the complete lower evaporator/heater core assembly to support the two separate temperature actuators (driver and passenger side) and temperature control valve, ACC head unit, ambient temperature sensor, a blower motor control module and blower motor. The ACC does not use a blower motor resistor but a control module and the blower motor is different.

The bottom line is it will be alot of work (labor intensive) and costly. Not to say it can't be done because anything can de done as far as mods or upgrades if you have the will, time, patience, knowledge and money.

BTW - Although it has been discussed in the past I know of no Grand Prix owner that has attempted or successfully done the switchover.

[Centrinomw]

Ok as I understand it, there is not a harness hidding or taped behind the regular harness. As example how there is a extra harness behind the DIC for example.

[BNaylor]

Not to my knowledge. The DIC harness was is an exception on certain year model Grand Prixs. If you remove the climate control head unit you will see the terminations/connectors for the appropriate head unit and I don't recall seeing any extra specifically for an ACC system if you have the manual.

Also, according to the GM wiring diagrams in the FSM the point to point wiring and color coding is different.

[Centrinomw]

Ok your right, thank you very much for all the help on this thread

[richtazz]

just to add a comment, I have the digital auto AC and it's not all it's cracked up to be. On auto mode, it doesn't seem to circulate enough air, so it feels cooler in the winter and warmer in the summer than the display indicates.

[BNaylor]

I guess it all comes out in the laundry Rich. The manual systems have much higher failure rates as far as the blower motor resistor and blower. One thing nice about the CJ2 ACC is the on board diagnostics mode.

That reminds me I recall the last major discussion we had on HVAC conversions was a member wanting to convert from the CJ2 ACC to the C67 manual dual zone. I believe it was Mike561. I guess he gave up on the idea after the replies.