Wiring a 24-volt Swamp (Evaporative) Cooler for Control With Relays
Brock,

I'm trying to set up the same for my MasterCool. It currently has the MasterStat CC1000 or CC2000 (not sure which model), for which you can find a manual at http://paseoalegre.com/index.php/download_file/34/.  My "MasterStat" control panel in the house has 4 wires which according to the manual work like this:


G: ground (have to identify the color, maybe grey?)
R: 24 VAC (not sure what this is for, but potentially to power the control panel?)
W: water pump control; 4-5 VDC to turn it on, 0 VDC otherwise
Y: blower speed control; 0 VDC for off, 2-3 VCD for low speed, 4-5 VDC for high speed


Then there is an appliance control board next to the MasterCool on the roof that translates these control panel inputs into the proper outputs to drive the motor and the pump.

Curious to hear if you learned more.