Temperature Control, Function

Function
The temperature set on the temperature dials is achieved or held constant by:
- Heating the air in the heater core
- Cooling the air in the evaporator
- Cooling and reheating the air (reheat mode)

Heating
The heater core heats the air flowing through it and on through the air ducts into the vehicle passenger compartment.

The heat given up by the heater core is regulated by the duovalves which control the flow rate of the heated coolant.

The duovalves are controlled by the pushbutton control module.

Cooling (automatic heater)
To cool the duovalves are closed, whereby heated coolant can no longer flow through the heater core.

Cooling (Tempmatic air conditioning)
The liquid refrigerant is injected into the evaporator under high pressure by the expansion valve expanding the refrigerant and reducing the pressure. The refrigerant then evaporates. The heat of evaporation required for this is taken from the air flowing through the evaporator. The cooled air then travels through the air ducts to the vehicle passenger compartment.

Reheat mode (Tempmatic air conditioning)
The air is cooled and dried in the evaporator and heated up again in the heater core (reheat mode). This prevents the windows from fogging up on the inside.