Quote:
Originally Posted by FritzR
I hate to hijack this thread but how hard would it be to put a vaccum activated control on the A/C On button so you could set it to come on at above a certain vaccum level? So if you are only pushing on the gas pedal less than a certain amount the A/C comes on.
|
That would be challenging. You would need a vacuum switch that opens under no vacuum, and closes under high vacuum. It would need to be adjustable so you could set it to allow operation while cruising, and this would require that you measure the vacuum under different conditions to see what level you would need the switch to trip at. Or, you'd have to drive and adjust for a couple of weeks until it was working the way you wanted. And, it isn't necessary on modern cars, depending on make and model the AC is controlled by the computer, and the computer cuts compressor power under WOT conditions.
Actually wiring it in is easy enough, you just mount the switch near the compressor, cut one of the compressor control wires, attach both ends to the vacuum switch, then run a vacuum line to the intake manifold. You need direct exposure to the intake itself, not a ported line.
Might also look at a thermostat that would cut power to the compressor when the temp is cool enough. Automobile systems use a mix of full AC and heater core air to adjust the air temp coming from the vents, meaning that you are cooling the air, then heating it back up again. By setting a thermostat inside the car (needs to be a DC powered operated thermostat, home thermostats sometimes use AC power) you can run the temp at max cool, then control how often the compressor cycles by the thermostat. Kinda like the idea of using a deep freeze as a fridge. You'd wire the thermostat in the same way, the only difference being you'd use a relay in the AC line, and a control line off the thermostat. This way you only have to run a single 18ga wire to the engine bay, not two 12ga wires to go from the AC wiring to the thermostat and back.