Mono valve electrical connection

[gregp1962]

The electrical connection to the mono valve was not floowing properly. So, of course it was blowing hot air on all settings. I rigged a connection so that the mono valve is activated whenever the key is turned on. Activating the mono valve stops the flow of hot coolant into the heater core. Now that we'll be getting cooler weather, I'll want to be able to turn on the heat without opening the hood to manually disconnect the mono valve.

What are the common reasons for the failure of the electrical connection to the mono valve? Also, I've heard that the switch is to the ground connection rather to the positive electrical connection. Is this true?