Electric Fan override switch

[ttikalsky]

I have a 1983 FC 33 with the electric fan on the motor, the type that
spins freely until the temperature reaches 189 degrees and then
engages (hopefully) by locking the fan to the pully. I would like to
add a switch so I could engage the fan when desired. I just replaced
the Alarmstat because the motor was overheating and the fan was not
engaging. I verified the fan engages when I ground the one of the
wires coming from the fan. I believe this is what happens when the
alarmstat reaches 189 degrees. There are 3 connections on the
alarmstat labeled "NO", "C" and "NC". The "C" connector has power at
all times. The "NO" has power when the key is on. Does anyone know
exactly how this works and has anyone added an override switch?

Troy, 83FC33