1990 SABLE with climate control

I posted about climate control system on the 90 sable. It works when 12 volts from the battery gives it power but the moment you start the heat and defrost shut down. I am 99.9% sure the resistor is the part needed. I saw a diagram in a Sable/Taurus Chilton book showing the resistor.Anyone know if this resistor is still in the supply chain? The Chilton book covered up to 95 Sable/Taurus. Or is there an aftermarket resistor available to make sure only 12 volts not 14 (as when the alternator comes on) will still flow to the blower motor. The climate control system has many vacuum tubes coming out of the back of the unit but none are at fault. The blower motor works fine and can be dialed to a snail pack or full bore. The temp is also variable. But at 14 volts the display is blacked out and no heat or defrost at all.