Wow! Thanks for helping that guy!
My 2000 TJ control assembly melted when it was just about out of warranty. The dealership replaced it with a USED one that was slightly less melted (claiming they couldn't find a replacement). I kind of got the feeling they just didn't want to deal with it.
Is there a way to add an additional relay to the wiring to take some of the heat load?
OK, the highest current circuit controlled directly by the switch assembly is the blower motor.
looking at page 8W-42-3, you can see that the positive/battery power to the blower motor is supplied through the BLOWER MOTOR RELAY and goes directly to the motor from there, so that side it "protected" by a relay. The ground side, however, is where they actually control the speed of the motor and it, following the line from the other side of the motor, goes to connector C7 of the A/C heater control, through the fan speed switch which selects the number of resistors and, therefore the amount of total resistance in-line with the motor (thus, selecting the motor speed) to tie directly to ground. In all four speeds, the full current drawn by the motor + resistor combination goes through the motor speed switch (contacts 7, 8, 9, and 10; connections C1A, C1B, C1C, and C1D). The high speed contact (7 / C1A) would be the one that would have to supply the highest current.
The only way to pass this current off to relay(s) would be to place one between the switch connection (C1A, C1B, C1C, and C1D) and its connection to the BLOWER MOTOR RESISTOR BLOCK. This would require a complete rewire of that switch in order to change it from acting as a power-director (choosing which path the current should take, through which resistors), to a relay control, controlling which of FOUR relays should be activated to make the same circuit connections.
If you are really interested in doing this, I could draw up a connection diagram to do it but, considering the work involved and the price and availability of aftermarket replacement control assemblies, I don't really think it would be worth it. I think you'd be ahead if you just bought a new assembly and held it in your spares in case your existing one ever fails...or just replace it now and be done.
