Manual Temperature Control

HEATING AND A/C SYSTEMS
A single-zone HVAC system is available on all JR series vehicles.

MANUAL TEMPERATURE CONTROL

HVAC Control
The HVAC system maintains incoming air temperature, airflow, fan speed, and fresh air intake for the entire vehicle from the instrument panel mounted A/C - Heater Control. The full range of temperature that the system can produce in any mode for the entire vehicle is available by positioning the blend Control to the desired range.

Air Intake
When the fresh-air door is open, outside air is drawn into the HVAC housing through the cowl opening at the base of the windshield. When the fresh-air door is closed, recirculated air is drawn in to the HVAC housing from under the instrument panel.

Air Distribution
The HVAC unit has four fully adjustable instrument panel outlets. Side-window demister outlets in the instrument panel eliminate the need for door ducts and door-to-instrument panel seals. A single, central mounted outlet delivers air for defrosting the windshield. Two ducts, one on each side of the center console underneath the instrument panel, provide airflow to the driver floor area and the front seat passenger floor area.

Mode Switch
The rotary Mode Switch has a total of eight positions. The first three, for A/C request, include Recirc/Bi-level, Panel, and Bi-level. The remaining five positions, for Heat request, include Panel, Bi-level, Floor, Floor/Defrost, and Defrost. The Floor/Defrost position and the Defrost position also provided an A/C request.

Mode Switch, A/C Request
Provided that the Blower Switch is in any of the four ON positions, rotating the Mode Switch to any of the three A/C request positions, the Floor/Defrost position, or the Defrost position, will result in the A/C - Heater Control sending a signal to the BCM to send a message to the PCM to provide A/C compressor clutch activation. However, the BCM will only provide this request if EVAP function is found acceptable.

Mode Switch, Mode Door Position Change Request
Provided that the Blower Switch is in any of the four ON positions, rotating the Mode Switch will result in the A/C Heater Control sending a signal to the BCM to signal the actuator to move the mode door. A potentiometer, inside the Mode Door Actuator, and feedback circuits provide the BCM with door position information.

Mode Switch, Fresh-air Door Position Change Request
Provided that the Blower Switch is in any of the four ON positions, rotating the Mode Switch to the Recirc position will result in the A/C - Heater Control sending a signal to the BCM to signal the actuator to close the fresh-air door. While rotating the mode Switch to any other position results in the A/C - Heater Control sending a signal to the BCM to signal the actuator to open the fresh-air door. When the Blower Switch is OFF, the fresh-air door closes to prevent outside air from entering the passenger compartment.

Diagnostic Trouble Codes
All HVAC Diagnostic Trouble Codes are stored in the Body Control Module. Stored DTCs indicate that a problem has occurred in the HVAC system, and may still be present. To verify a problem is still present in the HVAC system, use the DRB III to erase all stored BCM DTCs. After erasing the DTC(s), use the DRB III to see if the DTC(s) reappear. If necessary, actuate the A/C - Heater Control switches with the ignition ON and with the engine running while monitoring the DRB III to see if the DTC(s) reappear.