Temperature Control

Function
The temperature set on the temperature dials (automatic heater and Tempmatic A/C) or temperature buttons (automatic air conditioning) is achieved or held constant by:
- heating the air in the heater core
- cooling the air in the evaporator
- cooling and reheating (reheat mode)

Heating
The heater core heats the air flowing through which then passes through the air ducts into the vehicle passenger compartment. The heat given up by the heater core is controlled by the dual valves which control the flow rate of the heated coolant. The pushbutton control module controls the dual valves.

Cooling (automatic heater)
Cooling is accomplished by closing the dual valves preventing heated coolant from flowing through the heater core.

Cooling (Tempmatic A/C and automatic A/C)
The expansion valve located on the evaporator causes the liquid refrigerant under high pressure to expand reducing the pressure and allowing the refrigerant to evaporate. The heat of evaporation required for this purpose is absorbed from the air flowing through the evaporator. The cooled air then flows through the air ducts into the vehicle passenger compartment.

Reheat mode (Tempmatic A/C and automatic A/C)
After cooling and drying in the evaporator, the air is heated up again in the heater core (reheated). This prevents the windows from fogging up on the inside.