When I was testing the new configuration, I saw a minor issue - and you know how much those minor issues bother me...
There is an indicator light on the fan override switch which illuminates when you engage the switch. It's a quick visual reference when you have the fan override turned on. Here it is:
Notice in this picture that the switch is in the off position - but the A/C is on and that is triggering the indicator light.
Yeah, a little thing but it bothered me. I want that light to tell me that the switch is engaged - but it was telling me when the fan was being overridden.
The way this switch works is that the light is located on the cold side of the switch. When you turn it on, and send current to the cold side of the switch and on to its destination, the light illuminates.
Since I connected the A/C override relay to this same circuit, when that relay triggered 12 volts also comes back down to this switch and lights the light.
To rectify the light issue (pun intended), I added a rectifier diode the circuit. A rectifier diode allows electricity to only flow in one direction. I had a box of these things in my electrical stuff. The trigger circuit I added was 3amps, and I had a 3amp / 400 volt rectifier diode in the kit.
Then it was just a matter of pulling the dash apart (yet again), and adding in the rectifier to the outbound side of the override switch.
And then covering it with heat shrink. The rectifier prevents the current from flowing back to the switch (and the light) when 12 volts hits the circuit from the A/C trigger relay.
Now as I understand it, one consequence of using a rectifier diode is that they generate heat - especially as they approach the rated capacity. This circuit is drawing way less than 1 amp, so I don't think heat is going to be an issue.
But, if you are ever wheelin' with me and suddenly the rig bursts into flames - you will know why...
Anyway, it worked. Now the light comes on only when I hit the switch. Once again I can sleep at night (yeah, I've got problems...
).