Vintage Air AC light question

[parsonsj]

Hi guys,

I've got my old car II Much back, and I'm upgrading the electronics and related controls. One of the things I've done is I've removed the relays that Vintage Air uses to control the compressor and heater control valve and have instead connected the ground signal wires to inputs on the new Holley Dominator ECU. The Dominator, in turn, when it sees the AC request, makes sure that's all copacetic (rpm not too high or low, reasonable coolant temps, and not near WOT), and then tells a RacePak Smartwire to fire up the compressor.

All that works great. No issues at all in the cabin air temps.

Except that the AC light in the 3 knob slimline control panel is always on.

Anybody got an insight into why this might be happening? I'm wondering if there's a need for a pull-down resistor on the AC light circuit, but I wanted to check-in with the PT hive mind first.

thanks!

[CapSS92]

For the lighting there's a tan wire that controls the lighting. If that's not hooked up, then something might be backfeeding. I would isolating diodes on any ground wire to prevent this. Here's a link on diode info. If none of this applies, then their tech support is pretty good. Let us know what you find out.

https://www.the12volt.com/diodes/diodes.asp

Alex

[dontlifttoshift]

Is it always on or is it always ON? Does it get brighter if you switch to AC mode?

From the print, it looks like a simple 12v from the VA ecu and that light operates independently of actual compressor operation so I wouldn't think stray voltage from the Dominator connections would matter. I'm curious if the light goes out with the Dominator unplugged.

[KenSacramento]

I’m uniquely qualified to answer this question, the light is on because you are getting a 5v signal to the controller on the tan wire in the wire from the main unit to the controller, so even though the compressor is being controlled by your Holley, the signal is hot from the VA system. I’d drop a relay on the gray wire to only open when the compressor wire is hot.
This is not the tan programming wire, it’s the tan wire in the cable.



Here is the controller I built:

https://youtube.com/shorts/pyOLyw4R8mc?si=AOykfdJSmpKTsFqM217421

[Tim C]

Slight hijack, does anybody know what style connector vintage air uses for the control panel? I have cable slider adapters on my system and I'd like to add a wire to make a LED come on when the AC is on. My connector is missing the tan wire above.