How do you replace a Ford F-250 blower resistor?

Answer 1

First, what is commonly refered to as the blower resistor is actually a "package" of about 4 different sized resistors which are nothing more than spiral coils of different sizes, and of different sized wire. These resistors are mechanically mounted on a piece of electrically insulating fiber board. The piece of fiberboard is about 1/8th of an inch thick, 1 inch wide, and 1 1/2 inches long. The resistors are mounted on the "inside" surface of the board, and the outside surface has four blade type connectors pins to which the wiring harness plug is attached. The blower resistor package is mounted through a hole [slightly smaller than the fiberboard] on the "plenum chamber." The plenum is the large, sort of retangular plastic or fiberglass "boxlike" structure just below the glove box, and just above the passenger's feet. The purpose of the plenum is that it is a "box" in the air conditioning and heating system that houses the heater core, the air conditioning evaporator core, the "doors" for controlling air flow through the plenum, the attachment nipples for the various ducts going throughout the dashboard to the various distribution register outlets, and of course, the proper plae to mount the resistor package. The resistor package mounts to a hole in the plenum with two self-tapping [or sheetmetal] screws, one at each end of the package plate. If I remember correctly, these are hexagonal headed screws, and require a 5/16th or 1/4 inch wrench. A "socket driver" wrench is the easiest to use, but any wrench that properly fits the nut head will do. Remove the wiring harness connector from the old, defective resistor package terminals. Remove the two screws securing the resistor package to the hole in the plenum. Remove the defective resistor package, noting which way the blade connector pins are oriented so the replacement can be installed with the same orientation. This will make reconnection of the wiring harness connector easier. If you do not get the new package installed at the same orientation, it does not cause any insurmountable problem. The only issue will be that in reinstalling the wiring harness connector, your will have to twist the connector 1800 in either direction, so that the blade connector pins will be properly aligned with the slots in the harness connector. Install the new resistor package into the plenum, and reinstall the screws carefully and gently so that the steel screw threads do not strip out the delicate threads in the fiberglass plenum wall. Flush and snug is tight enough, no hard tightening required. Finish by carefully, and with the correct orientation of the pins, reinstalling the wiring harness connector plug to the connector blades sticking out of the resistor package.