Binary A/C switch fan activation

[Bad Bowtie]

Ok guys need some advice here. So I have a c6 Z06 fan setup with the factory pwm controller that is going to be controlled by my Holley Dominator ECU and I start thinking about my A/C pressure switch / binary switch that will be wired into my Vintage Air system wiring. So, where I believe I'm going to run into issues is generally you would run a trinary switch to turn on the cooling fan when the A/C is engaged thus overriding the temp sensor on a non-PWM setup. I don't know of a way to go about wiring the binary switch into the system that is controlled by PWM.

Example... let's say I crank the car but it's not up to temp or below the pre-determined fan on temp setting, now I turn on the A/C without the fan running and my ac pressures rise due to the lack air going across the condenser and builds pressure to the point the binary switch shuts off the ac compressor, I need to figure out how to wire this binary switch into a PWM system to engage the fan when I turn the A/C on.



Hoping some of you guys using PWM fan setups can help me get that "light bulb moment" and figure this out.


Thanks
BB

[sccacuda]

If the pwm controller is activated by an output from the Dominator ECU, you could use the A/C pressure switch as an input to the Dominator, then just configure the software to use the fan PWM output to also use the A/C pressure input to control the fan as well. You'll have to find the pressure to voltage scale of the sensor and then setup your PWM % to correlate. Alternatively, you could just use an A/C input "on" to the Dominator to turn the fan on, but this would probably have to be an all or nothing thing, with the fan on 100%.

[dontlifttoshift]

If you have an AC pressure sensor you do not need the binary switch at all. AC clutch turn on can be an input into the dominator from your AC controls. Then the dominator can output to the clutch if pressures are within a specified range. This is my preferred method when I have the I/Os available.

or

If you have a trinary switch, wire it normally but the fan control side runs through the dominator and add it as an input to your pwm table. For example the trinary switch closes and the fan runs at 30%. This is what I do on Terminators when I am I/O limited.

[Bad Bowtie]

Thanks Craig & Donny,
I'm sort of new to the Dominator and EFI so still navigating my way through the input and outputs and the amazing things it can do. This info gave me a couple of new ways to look at the system and figure which one works best for me. Glad this is the last tidbit i need to sort out. The system so far has been relatively simple and I can say that only because I haven't fired it up yet .

Appreciate it guys.

Jack