OK, after trying all of the above and blowing fuses and generally stuff not working, I called an car electronics guy and here goes. The switch is not hot, it controls the ground so if you wire the relays as follows IT WILL WORK!
Terminal 30 to ground, the radio one works great.
Terminal 85 to the outlet from the control switch on dash
Terminal 87 to the fan resister
Terminal 86 to the power source, the add a fuse thing worked great, i used the cig lighter position, this is just control power for the relay.
Again you have use the ground wires like power and power like ground. For all of us mechanical folks that aren't tron jockeys hope this helps. I used the prolink stuff.
To bring up an old thread...
Just completed this as shown by the OP, works awesome. Now I hope never to worry about melted fan switches again.
It's supposed to be -6 overnight here in MI haha this winter was just brutal with only fan speeds 1 & 2 working!!
This fix is really just a placebo...The problem is, it just moved the issue from one location to another. The entire problem with the melting connector is due to overheating from loose/corroded connections. The reason it works well now is because you established all new connections, and not because of the relays. If the connections at the relays become loose or corroded like they were at the switch, they will also overheat.
http://www.fourwheeler.com/how-to/el...205-safe-heat/ Found it. They basically say the fix lasted 20,000 miles. So what did they do? Replaced everything. Switches, fan and resistor (blower motor) not add on ones they created before. Basically went back to stock but all new. They figure all new factory stuff will get them 100,000 miles. I think they are dreaming. If your on a smart phone you have to click the first pic in the link then swipe to next pic and so on for the new fix. Although it's moot as we replace that stuff all the time. I stuck heatsinks for ram boards on mine. I've been good for a long time
Just FWIW, The blower motor drawing 20 amps in their write up is not what caused their problem either. The blower motor fuse and circuit wiring is rated for double that amperage at 40 amps. The one and only issue here is loose/bad connections at the switch. The spade connectors get loose over time and a loose connection creates a lot of resistance (like using too small a wire in a circuit), That resistance produces heat, and that heat, melts plastic. Even though the circuit is passing fewer amps than its rated 40 amps (so the fuse doesn't blow), it's still more than the bad connection can carry without burning up.