I have a 1968 Camaro with factory A/C. The fan only goes to 2 speeds instead of three. No high speed or maybe no low speed-not sure which. Thinking of the fan resistor as the culprit but I don't know where it is located. Any help would be appreciated.

 

The picture below is from the 1969 Service Manual, but I'm pretty sure the 1968 heater is similar.

 

High speed is direct battery power. Other speeds go through a resistor network as shown.