Electronic HVAC retrofit into G-Body

[Doober]

For now it's just planning stages, but recent posts have me thinking about it again... eventually my plan is to swap a more modern HVAC control setup into the Malibu, though it will look slightly out of place having a different button style than the factory.

From another post:

... it appears they still used the awful vacuum control into the '90s on some cars.

My plan involves the controls for the late '80s/early '90s GM trucks (GMT400 platform), possibly the late '90s if the controls are still the same and the control head isn't too big.
Early GMT400

Late GMT400

I started doing some looking and discovered they use a motor similar to the NBS (GMT800, '99-'06) and possibly newer trucks.

The early controls used relays to run power through each blower speed resistor, I'm not sure about the later ones though... it's not real clear but you can see the relay bracket here (behind where the glove box mounts):

My thought is it should be possible to just tie it in place of the factory G-Body relay module in the engine compartment, matching the speed settings up to the relays for the newer controls, since many/most of the GMT400 trucks had 4 speeds like the G-Bodies (not all, I had an '88 Chevy with manual heat/defrost controls and low/med/high with a mechanical switch).

 

[Ribbedroof]

After seeing the failures on these and the Ford actuators (wife's Flex is on it's third one in 3 years), I'll be sticking with the old reliable cable for the blend door and hope for the best on the simple G body mode switch.

Hopefully, you won't encounter the failures we're seeing....those later control heads are not cheap nor have we had any luck with salvage units.....then there's the whole "national backorder" issue on some of them.

 

[Doober]

I've seen issues with the newer ones too (in our '02 Silveraro actually)... but I've never seen an issue in the old style ones... my '92 is still kickin' around fine, and my parents' 2 past Suburbans never had problems.

 

[TURNA]

The Buick Regals came with an electronic control why not just use that ?

 

[Doober]

It still uses the vacuum lines with some sort of electronic valve control I believe, probably similar to what this guy used to swap digital controls in from a mid '90s Caprice

 

[pinstripebob]

Did you end up swapping in other controls? I'd be curious to see the end result of this.

 

[Doober]

No, I haven't messed with the Malibu in any capacity in quite a while... last time I did anything was changing the clutch, painting the shifter stick & floor black, and putting seat covers on to make it look semi-presentable for my wedding last summer. It's still something I'm considering though, but that will involve pulling the dash back out again... probably will eventually anyway.

I still have to tie the wiring in for an alarm, and it won't be the typical brain-under-the-dash setup... it will be hidden and the wiring will be hard to find. I also plan on tucking a second siren up under the dash that will trigger independent of the regular siren. Basically while the alarm is armed, the siren will have a ground. If the column is broken & ignition turned on, the siren will run non-stop while the ignition is on, and the only way to disarm is to disarm the alarm or to kill power to it... good luck finding it quickly.