Your observation that it can be made to work indicates the switch has burned contacts. You can expect to also find at least two black and melted terminals in the plug. The fix is to replace the switch and to cut out all overheated terminals. One solution is to buy a new connector at an auto parts store. You also can find a good used one from a car in a salvage yard. In your car, the overheated terminals will have wires that are hardened for about the first four inches. Solder will not adhere to that part so it must be cut away, then a four-inch section of new wire, the same diameter, must be spliced in. Always seal those splices with heat-shrink tubing. Never use electrical tape in a car as it will unravel into a gooey mess on a hot day.
You can also just cut out the overheated terminals and the melted part of the connector body. Splice in the new four-inch piece of wire, then install a universal crimp-type terminal, but also solder it for the best connection. Plug those onto the new switch individually.
It is important to understand that you must do the entire repair. Replace the switch and replace the overheated terminals. If you only do half of the repair, the part you leave alone is going to have excessive resistance which translates into heat when current flows through it. That heat is going to continue to migrate into the part you just replaced and cause a repeat failure. This damage occurs most often when the fan is used on the highest speeds often. It also causes the same type of failures to the ignition switch, and more so if the ignition switch is turned on or off when the fan switch is set on a high speed. I never used the two highest fan speeds on my old 1988 Grand Caravan, and rarely the second speed. The switch never failed once in over twenty eight years.
Mar 11, 2018 at 6:20 PM
