GF83.57-S-2000A | Temperature control, function | 19.8.98 |
MODEL 638.094 /194 with CODE (H17) Residual engine heat utilization
MODEL 638.094 /194 /294 with CODE (H06) Air conditioning
MODEL 638.294
The temperature set on the temperature selection knob (A20s1, models 638.094 and 638.194) or on the temperature selection digital switch (A20s8, model 638.294) is achieved or held constant by:
Heating up with the heater core
Cooling with the evaporator
Cooling and reheating (reheat mode)
Heating up
The heat exchanger heats the air flowing through to the air ducts and into the passenger compartment. The heat supplied by the heater core is controlled by the heated coolant quantity flowing through via the cycle valve (Y37, automatic heater).
The cycle valve (Y37) is actuated via the air conditioning pushbutton control module (A20).
Cooling (automatic heater)
Cooling is accomplished by closing the cycle valve (Y37) preventing coolant from flowing into the heater core.
Cooling (Tempmatic)
The high pressure of the liquid refrigerant is reduced by expanding with the expansion valve on the evaporator. Then the refrigerant evaporates. The heat required here for evaporation is absorbed from the air flowing through the evaporator. After cooling the air flows through the air ducts into the passenger compartment.
Reheat mode (Tempmatic)
The air is cooled and dehumidified by the evaporator and then reheated by the heater core. This prevents the windows from fogging up inside.