Chevrolet Repair: ported vacuum switches, coolant, thermometer

Question
1979 chevy,how do you test?

Answer
Hi Robert, The first thing you need to know is what ports the switch is going to open or close. Now you need to know at what temp that switch is going to perform these actions. The temp is on the part that is in the coolant, there will be numbers like 160  170  etc. Now you put the switch in hot water with a thermometer and at the temp on the bottom of the switch it should open the ports.

     Sounds like a lot work right,it is. Might be easier to replace the switch.

     Hope this helps            Mark