Circuit Operation

When the Ignition Switch is turned to "RUN," voltage is applied from I/P Fuse 11 to the H-A/C Control. When the Rear Defogger Switch is pushed to "ON," voltage is momentarily applied to the Rear Defogger Solid State Timer through CKT 39. When voltage is applied to the Rear Defogger Timer, the Solid State Timer will close the internal contacts. The internal contacts remain closed until the defog cycle is complete or the Rear Defogger Switch is pushed "OFF."

When the internal contacts of the Rear Defogger Switch are closed, voltage from I/P Circuit Breaker #4 is applied to the indicator and to CKT 293, the Rear Defogger Grid and I/P Fuse 44 if equipped with heated Mirrors.

The H-A/C Control contains an internal timer to control the time the internal contacts are closed. When the Ignition Switch is turned to "RUN" and the Rear Defogger Switch is pushed to "ON" for the first time. the defog cycle lasts 10 minutes. Further operation will result in 5 minute defog cycles. The defog cycle is reset to 10 minutes when the Ignition Switch is turned to "OFF" and back to "RUN."