Stupid, difficult electrical failure solved

[rich weyand]

Yeah, the post was just a reminder to people not to assume that all the wires are good.

Update: While I had the dash apart, I replaced the heater control assembly, lubed all the cables, lubed the pivots on the three air doors, cleaned up the clearance issue on the defroster air door, fixed the light for the heater controls, sealed up the 1/2" gap between the heater box and the defroster duct with metal tape, and replaced the (broken) shift indicator cable. All heater controls are silky smooth now, I have full speed from the blower fan, and I have a whole lotta defrost air.

I think that defroster duct gap is very common on these trucks. It may even have been designed in there for some reason. You should check. It's at the top of the heater box just above the transmission hump. The forward side is pretty much up against the firewall insulation, but it's pretty easy to seal the other three sides with some of that aluminum tape.

Also, if you have a skreetch when going into or out of defrost, the air door is scraping on the sheet metal forward side of the heater box. That sheet metal can be persuaded to be a little more forward and better clearance the door by pushing it forward (toward the firewall) with a long blade screwdriver and pounding on the handle with the heel of your hand. To get at it, remove the little air deflector that aims air to your feet. There is one hex screw installed vertically on the passenger side flange of that little deflector. Give the sheet metal forward plate of the heater box a hit every inch or so along the bottom edge until the defrost door has clearance.

Truck is all back together now.