Air Delivery and and Temperature Control

Diagnosis: Table 2 C36 And C34 Component State:

HEATER AND A/C CONTROL ASSEMBLY
With the ignition Switch in "RUN, voltage is applied through the IGN Fuse to the Heater and A/C Control Assembly. The operating mode of the system is determined by push button switches on the front panel. Output voltages determine which air valves are to be operated as well as the position of the Air Temp Valve.


SOLENOID BOX
The Solenoid Box contains the solenoid valves that control the vacuum actuators. When the solenoids are de-energized, the valves vent the vacuum actuators, allowing the vacuum actuator to return to the "VENT" position.

RECIRC VALVE
The RECIRC Valve closes off the outside air inlet so that the air from the inside of the vehicle is recirculated through the A/C System for maximum cooling. The outside air inlet is closed when vacuum is applied to the actuator. When the vacuum actuator is vented, the RECIRC Valves close off the in-car air inlet which allows outside air to be drawn into the vehicle.


AIR TEMP VALVE
The Air Temp Valve determines how much air flows through the Heater Core, which determines the temperature of the air to the outlets. It is moved by an electric motor which is part of the Temperature Door Actuator. The position of the valve is determined by the voltage at the output of the Temperature Lever in the Heater and A/C Control Assembly.


PANEL VALVE
The Panel Valve determines whether air flow will be directed to the panel outlets. With no vacuum applied to the actuator, the valve is positioned to allow no air flow to the panel outlets.


DEFR VALVE
The DEFR Valve determines whether air flow will be directed to the windshield defrost outlets. With no vacuum applied to the actuator, the valve is positioned to allow air flow to the windshield defrost outlets.


HTR/DEFR VALVE
The HTR/DEFR Valve can assume three positions and is operated by a bi-directional vacuum actuator which can move the valve to either of two positions. If no vacuum is applied to either vacuum actuator, the valve is in mid-position. Air flow with the valve in mid-position will be delivered to the defrost outlets and the floor outlets. When the HTR Vacuum Actuator (red vacuum hose) is operated, the valve is positioned to direct air flow to the floor outlets and slight air flow to the defrost outlets. When the DEFR Vacuum Actuator (yellow vacuum hose) is operated, the valve is positioned to direct air flow to the defrost outlets and slight air flow to the floor outlets.


REAR VACUUM DOOR
The Rear Vacuum Door is activated by vacuum originating from a "tee" in the "DEFR" vacuum line. With no vacuum applied, the Rear Vacuum Door routes air to the floor and window vents.


WATER CONTROL SOLENOID (C36 AND C34 ONLY)
With the Ignition Switch in "RUN," voltage is applied to the Water Control Solenoid through the IGN Fuse. In the de-energized state, vacuum is applied to port 1 of the Water Control Valve through the Water Control Solenoid. When energized, the Water Control Solenoid vents port 1 of the Water Control Valve. To energize the Water Control Solenoid, the Front Mounted Auxiliary Blower Switch must be in the "OFF" position, or the Rear Mounted Auxiliary Blower Switch must be in the "OFF" position with the Front Mounted Switch in the "RR CTRL" position. The Water Control Solenoid may also be energized if the Heater Control Assembly is in the "OFF" position and the Auxiliary Blower Switch is not in the "OFF" position. During normal fan operation, the Water Control Solenoid is de-energized.

WATER CONTROL VALVE (C36 AND C34)
The Water Control Valve is a three-position two-vacuum port water valve that regulates coolant flow to the rear compartment heater core. Its three positions (Wide-Open, Restricted and Closed) are controlled by vacuum applied to ports 1 and 2 of the valve. The application of vacuum to these ports is controlled by the Water Control Solenoid (port 1) and the Heater Control Assembly (port 2). When the Water Control Solenoid is energized, port 1 of the valve is vented and port 2 is mechanically overridden, causing the valve to be in the Wide-Open position. This position is required for filling the cooling system. With the Heater Control Assembly in the "HTR-DEF" Mode ("OFF," "HTR," "DEF," "MIX") and the Auxiliary Blower Switch in an "ON" position, vacuum is applied to port 1 and port 2 is vented, causing the valve to be in the Restricted position, limiting coolant flow to the rear heater core. The Rear Vacuum Door will direct air to the floor and window vents. Placing the Heater Control Assembly in the "Upper" Mode ("MAX," "A/C," "VNT," "B/L"), both ports 1 and 2 have vacuum applied, causing the valve to be in the "Closed" position, preventing coolant flow to the rear heater core. The Rear Vacuum Door will route air to the overhead vents.