Fun with Fan speed controller

As luck would have it, the fan speed controller was bad for the AC. At first I suspected it may be the transistor mounted in the air duct, but after swapping one of the heater fan controllers and seeing the fan worked fine, I new the problem was in the controller. I disassembled the controller and found it was a PWM type speed controller using a 555 timer chip. The arrow here points to the 555
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The only other non-trivial component was a BD-238 transistor. Otherwise, the board only contains resistors, diodes and capacitors
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The symptoms were the fan wouldn't turn on at all with this controller. After talking with a friend, the idea suddenly hit me that the contacts on the on/off switch may not be contacting. I checked with an ohm meter and sure enough, open circuit. Sprayed the switch area as good as possible with contact cleaner and after working it a few times, success! I observed the AC clutch also engages when the switch is turned on. Tomorrow will be a test of the AC charge to see if it has proper refrigerant charge
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