The temperature valve actuator operates in response to a voltage signal from the heater and A/C controller's temperature control knob. When the ignition switch is in the RUN position, operating voltage is available to the temperature valve actuator motor from HTR-A/C fuse 12 through CKT 141 (BRN). The motor grounds to ground G201 through CKT 150 (BLK). The motor positions the air temperature valve in a position consistent with the voltage signal from the heater and A/C controller. The actuator motor receives the signal in CKT 733 (LT BLU).

The heater and A/C controller also receives power from the HTR-A/C fuse 12 through CKT 141 (BRN). The heater and A/C controller also grounds through CKT 150 (BLK) to ground G201. In the controller, current flows to ground through a rheostat. The temperature control moves the wiper arm of the rheostat in order to select a portion of the voltage dropped across the resistance. The actuator motor receives the voltage in order to position the valve.

A single front auxiliary HVAC control module located over the instrument panel (IP) controls the cargo van's auxiliary A/C air delivery and temperature controls. Both temperature control and mode control for circulating the inside air is possible. The rear auxiliary mode valve directs air either through the overhead vents or through the lower vents along the left side of the rear compartment. The rear auxiliary temperature valve directs the air flow either through or around the heater core in the rear auxiliary ventilation system.

Electric motors control the positions of both valves. Both the rear auxiliary mode valve and seal assembly and the rear auxiliary temperature valve assembly receive operating voltage through CKT 341 (BRN) from RR HVAC fuse 24. This voltage is available only when the ignition switch is in the START position or in the RUN position. Both valve assemblies ground through CKT 150 (BLK) to ground G400. Each valve assembly positions in response to a voltage signal from the rear auxiliary HVAC control module. The rear auxiliary mode valve and seal assembly receives the positioning signal through CKT 733 (LT BLU). The rear auxiliary temperature valve assembly receives the positioning signal through CKT 734 (DK GRN).

The rear auxiliary HVAC control module also receives power from RR HVAC fuse 24 through CKT 341 (BRN). The rear auxiliary HVAC control module also grounds through CKT 150 (BLK) to ground G401. In the control module, current flows through 2 parallel rheostats. The temperature control dial moves the wiper arm of one rheostat. The mode control dial controls the wiper arm of the other rheostat. The wipers select a portion of the voltage dropped across each resistance. The connected actuator motor receives this voltage in order to position the valve.

The passenger van's air delivery and temperature controls operate in a manner similar to the controls of the cargo van. The difference is the passenger van has two control modules and an A/C control logic module.

The front auxiliary HVAC control module is over the IP. The rear auxiliary HVAC control module is overhead behind the front seats. The heater and A/C control logic module is overhead, just ahead of the front auxiliary HVAC control module. The front auxiliary HVAC control module's blower switch has an additional rear CNTL position. With the selection of the rear CNTL position, control of the rear auxiliary mode door is from the rear auxiliary HVAC control module. With the front auxiliary HVAC control module in any other position, the rear auxiliary HVAC control module has no control.

Each control module receives power from RR HVAC fuse 24 through CKT 341 (BRN) when the ignition switch is in the RUN position or the START position. Each control module grounds through CKT 150 (BLK) to ground G400. Each control module has a pair of rheostats for temperature and mode control. The voltage developed at the wipers of these rheostats routes to the heater and A/C control logic module. CKT 734 (DK GRN) delivers the temperature control signals. CKT 733 (LT BLU) delivers the mode control signals. If the front auxiliary HVAC control module is not in the rear CNTL position, the relay in the heater and A/C control logic module remains de-engergized. The signals from the front auxiliary HVAC control module then route through the normally-closed contacts to the valve actuators.

When the front auxiliary HVAC control module is in the REAR CNTL position, a ground path is available fro the heater and A/C control logic module's relay coil. Because the heater and A/C control logic module's relay coil receives voltage through CKT 341 (BRN) from RR HVAC fuse 24, current flows through the relay coil, through CKT 203 (LT BLU) to the front auxiliary HVAC control module. Current then flows through the rear CNTL contacts in the control module and continues to ground G400. The coil energizes. The contact change state in order to connect the positioning voltages from the rear auxiliary HVAC control module to the valve actuators.