Medium Speed Fan Circuit

CAUTION: Do not use a meter with an impedance of less than 10 Meg ohms.

1. Set the blower speed to MEDIUM.
2. Insert the positive probe into terminal A (circuit 50) and the negative probe into terminal M (circuit 951). The voltage should read 11.5 to 12.0 volts. (This indicates that the controller is providing a ground to the LO speed fan relay.)
3. Move the negative probe to terminal L (circuit 963). The voltage should now read 0 volts. (This indicates that the controller has removed the ground for the HI speed fan relay.)