Chart 9 Rear A/C Blower Inoperative

CIRCUIT DESCRIPTION
Power from fuse "C9" is applied thru relay "E," energized by fuse "A3," to blower and ground is supplied through the switch. The blower speed is controlled by varying the circuit amperage using a series of three resistors contained in a module. The Air Conditioning Programmer (ACP) receives a feedback voltage signal (AD70) but this has no bearing on rear blower operation.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. If CKTs 52, 850 and the "HI" position of the switch have continuity then AD70 will read nearly zero. As increasingly slower speeds are selected, the blower motor ground path passes through more series resistors in the module and results in increasing voltages at S316 and will measure battery voltage in "OFF" or if no ground path exists.
2. If a resistor in the module is open, all cavities beyond that point will also be open. If cavity "E" operates blower, then fault is in the switch or wiring to the switch.