How to install blower motor relays??

It is mainly the "blower high" position that melts the switches, so I put a relay for that position alone in my 69 Dart and 65 Newport. That was after melting both the pneumo-electric push-button switch and the L-M-H switch. Below are sketches I made of the wiring. Can't give details since this was c.a. 1993, but same as above, use the "blower high" wire to turn on the relay coil (86, 85 to gnd) and wire the relay output (87) to where the "blower high" wire was going. Supply the relay w/ 12 V from ACC circuit (to 30, sideways pin).

I include the pneumatic plumbing since was fooling with the push-button, and also had to figure how to use a 5-button to replace my Newport's 4-button (unobtanium). The Dart was a factory AC car.

BTW, this is hardly a Mopar thing. 1980's M-B cars like to melt the #8 fuse-holder (blower). Indeed, just today I was wiring a relay to power the "blower relay box" in my 1984 300D (like I did in my 1985) before its fuse-holder melts (like my 1985 did).

A funnier blower story. My dad checked the blower fuse in our 70's Matador wagon and "looked good" (no frebbie HF multimeters then) so he put it back and we suffered thru 5 summers in FL w/o AC because "too expensive to fix". He finally found the fuse was open and melted right at the tip where not visible, not from over-current but rather heat from the corroded terminal in the fuse-box (this was FL). Changed the fuse and we had AC again. Actually, he put in a breaker-type fuse that resets automatically.

Moral is you have to redesign this stuff in many cars. The manufacturers are striving for a price point, and just have to meet the warranty time. The new electronic blower controls are better, but even the one in my 2002 T&C failed (common problem) and a replacement "resistor pack" (actually transistors) cost $60, but it was a better redesign.