90 Ranger with intermitant blower motor

[mtk51]

I have a 90 Ranger and the blower motor has started acting up. More often than not, the blower motor will not run with I turn the fan switch on. Sometimes, after about a half hour of driving or more, the blower will start running.

I have replaced the relay and have removed the blower motor and bench tested it with a 12 volt battery. It runs fine and doesn't seem to bind or be damaged in any way.

I pulled another part out of the blower housing which has three wire coils on it. I assume these are the resisters to control the different motor speeds. It, and its contacts, are very rusty. The battery in my multi-meter is dead, so I haven't checked the resisitance.

A related or maybe not related point. Recently, the truck antitheft device started to trigger and not let me start the truck. A dealer finally traced it down to a bad relay. The no start trouble was cured, but it was the next morning that the blower started acting up. Maybe related?

1. Any experience/ideas on what to check?
2. Anyone have a wiring diagram so I can trace the electrical?

Mark in Minneapolis

[goon]

First of all the three coil wires is the resister for the fan speed and the fan will work on high if the resister is not working. It sounds like you have a dead spot in the fan motor. Next time it doesn't work tap the motor when the switch is on if works replace the motor.