Function of auxiliary coolant heater (ACH)

W83.70-0164-09

1 Heater
2 Fuel metering pump

5 Combustion and hot air blower
6 Heater core

3 Timer
4 Control circuit board

Function

 The stationary heater (1) is switched on directly on the timer (3) or by setting a time on the timer. The control circuit board (4) for the heater then starts up the heater. The speed of the combustion/hot air blower (5) and the fuel metering pump (2) are regulated correspondingly when started. The fuel metering pump takes fuel out of the vehicle tank and transports it to the heater. Here it forms an explosive mixture together with the combustion air from the combustion air blower and is burned in the heater. The heat from combustion can then be used for heating.

 Air is blown around the exterior wall of the heater core (6) with the aid of the heater blower. The heated air from the heater core is then blown back into the interior.

 The desired interior temperature can be set on the timer. The interior temperature is controlled thermostatically by the control circuit board (4) in combination with the system's own temperature sensor.