New problem in the last month: The squirrel cage fan that blows the defrost and heater was blowing strong, but now blows less strong most of the time, but occasionally will blow at full speed. The fan speed selector seems to work OK when it is blowing at full speed. The charging system seems OK. That is, with all accessories, lights and window defrosters, AC (and everything else I can think to turn on) on it doesn't seem to make a difference.

Where should I start with troubleshooting? Switch, fan or power source?

thanks

New problem in the last month: The squirrel cage fan that blows the defrost and heater was blowing strong, but now blows less strong most of the time, but occasionally will blow at full speed. The fan speed selector seems to work OK when it is blowing at full speed. The charging system seems OK. That is, with all accessories, lights and window defrosters, AC (and everything else I can think to turn on) on it doesn't seem to make a difference.

Where should I start with troubleshooting? Switch, fan or power source?

thanks
Go to a auto parts stor have them check your battery and alt. And if that is not it, it is probly you fan motor.