Dart "Cool Aire" A/C

67Dart273 said
Almost impossible to say without knowing exactly what you have now. Some of these add--on systems are as simple as a blower switch, probably multi speed. You may have or need a blower resistor for low speed, a switch to control the compressor, with a cap tube thermostat, possibly a low pressure cutout switch on the low side of the system, which simply goes in series with the clutch.

Thanks, 67Dart. The Cool Aire was a dealer installed option. It has a multi speed blower, with two resistors to give three speeds. The thermostat with capillary tube controls the compressor. When I convert it to R-134, I'll add the low pressure switch.

The help I'm hoping to find is what color wire goes to which switch terminal and what the black wire paired with the blue that goes from the thermostat to the compressor. I'm thinking maybe that black wire is power in to the whole unit. I'd like to know that for sure, and which switch terminal does it connect to.

KitCarlson said
Silicone spray lubricant is very bad for electrical switches. It may be too late. Perhaps use CRC electrical parts cleaner. It can be found at auto parts stores. I learned this at MicroSwitch, where silicone spray was forbidden from the plants.

There is nothing too fancy about compressor control however it takes several amps to engage the clutch. When cool enough, the thermostat opens the connection. The clutch is very inductive, so opening load is hard on switch contacts. The on off switch is in series, the fan switch powered to run any time for circulation. The fan should always run if a/c is on.

Thermostats easily fail if constantly adjusted, the diaphragm work hardens. Best to leave set. I would wire in a 30A Bosch relay to save the thermostat contacts. Battery to 30, clutch to 87, 86 to thermostat where it would have supplied clutch, and 85 to ground.

Thanks, Kit. I'm going to flush the switch with CRC as you suggested, Then what do I lube them with? The switch was very gritty and hard to operate from many years in the Arizona sun. I flushed it with WD40, then carb & choke cleaner. Then I added the silicone and the operation of the switch is now smooth and the terminals do connect properly when I press the buttons.

I hadn't thought about switch opening arc due to the inductive nature of the clutch. I'll use your relay idea. Leaving the t'stat set kinda defeats its purpose, doesn't it. Depending on ambient air temp and other factors, thermostats get adjusted. At least mine do. I'm looking for new thermostats, because I have no idea how long the working ones I have were in service. Thanks for the info, I hadn't thought of the metal diaphragm work hardening. All info is appreciated and added to my fund of damnnear useless data.

ATB

BC