[ron427]

Ron
The only thing I can think of that is common with the three gauges and the heater fan is 12 volt ign power or ground.
All the gauges except the ampmeter are powered through the constant voltage regulator that is mounted near the center of the instrument cluster. The mounting screw for the regulator usually goes into the printed circuit and provides a ground for the regulator.

The IVR actually provides a "pulsating 12 volts" at the on-off frequency near that of a turn signal flasher and gives an average of about 7 volts. If working properly you should be able to test at the input side of any of the three gauges with a test light or analog voltmeter. Also while in the "failure mode", see if you have 12 volts to the heater motor. If you have a good jumper wire, try running an aux. ground from heater motor or gauge cluster to battery ground. As you probably know, a loose ground can give a conbination of problems you would never dream of. I see no way the regulator can directly effect the wipers or heater.

I am retired and usually home. Call me at 318-343-7158 if I can help.

Nice car and good luck.

Ron Johnson