blower resistor block plug melting around dark green wire

[wolf100x]

I have a 72 charger with ac.
The blower only works on defrost and heat but is dead on vent, ac and max ac, I noticed the plug on the blower resistor block was melting around the dark green wire.
I swapped the resistor block with one from a 73 ac car and it made no difference...
Could this be a control switch problem? What should I check next?
 

[Nacho-RT74]

tipical...
however as a default, once you turn on the AC and vent even without fan lever switch plugged IT SHOULD TURN ON on low speed.

you must have some problem coming out from control unit selector.

how it works:

AC system gets two input sources, one to feed clutch ( coming from acc source ) the other one to feed blower ( coming from fuse block )  BUT in two stances

The two outputs to blower are:

The the green one runs to fan lever to select the speed, but at the time is spliced to resistor in LOW speed. When you select Mid and high speed, by Ohms law, the load goes to the smaller resistor selected to run the propper speed, no matter if green runs also straight up top low speed ( bigger resistance ) at the same time.

THAT IT MEANS if you don't have low speed fan no matter if fan lever is unplugged, there is something wrong on main switch selector at green output OOOOR... resistor is damaged.

Try to jump the green output from main control selector switch to the green wire what feeds the blower ( it should be arriving to bulkhead block to NSS harness section ). If blower works, control switch is good and resistor or related parts such as plug or wire is bad.

Brown to heater and def and are fixed speed, not selected by lever blower switch, so comes out straight from control switch to resistor. The only change on these functions it happens at vacuum actuators.

I hope it reads clear