GF83.70-P-3067A Switching Between Heating/Stationary Ventilation, Function

Switching Between Heating/stationary Ventilation, Function
- with CODE (228) Stationary heater [models 203 up to 23.4.04, 209.3 up to 31.5.04, 215 as of 1.6.00 up to 31.8.02, 220 as of 1.6.00 up to 31.8.02, 230.4 up to 08]

Component Identification:

Function sequence
1. The STH heater unit or the STH or HB [ZUH] heater unit (A6) operates in partial load or full load mode. The indicator lamp in the STH switch (N72s12 or S46) lights up. The coolant heated up in the STH heater unit or in the STH or HB [ZUH] heater unit (A6) flows through the heating and coolant circuit. At a coolant temperature over 30 °C and below 72 °C the blower motor delivers preheated air into the interior; it is activated by the control and operating unit (N18, N22 or N22/7).
2. The interior temperature exceeds the temperature value preset on the control and operating unit (N18, N22 or N22/7).
3. The control and operating unit (N18, N22 or N22/7) sends the "ventilate" signal over CAN-B (CAN-B) to the STH control unit or the STH or HB [ZUH] control unit (A6n1).
4. The STH control unit or the STH or HB [ZUH] control unit (A6n1) actuates the heater run-on to cool the STH heater unit or the STH or HB [ZUH] heater unit (A6) and for flushing the combustion chamber.

The duration of the heater run-on is geared towards the given operating condition:
^ Partial load operation approx. 160 s
^ Full load operation approx. 170 s

5. The blower motor now delivers air that is not preheated into the interior. The indicator lamp in the STH switch (N72s12 or S46) displays the actuation of the stationary ventilation by flashing on and off. The in-car temperature falls or remains constant.

6. The interior temperature drops below the temperature value preset on the control and operating unit (N18, N22 or N22/7).
7. The control and operating unit (N18, N22 or N22/7) sends the "heat" signal over CAN-B (CAN-B) to the STH control unit or the STH or HB [ZUH] control unit (A6n1).
8. Heating operation is started again by the STH control unit or the STH or HB [ZUH] control unit (A6n1). The indicator lamp in the STH switch (N72s12 or S46) is set to steady light again.
9. Once combustion has stabilized, the interior is supplied again with preheated air over the blower motor.

During a heating phase, switching between stationary ventilation and heating may occur several times, depending on temperature behavior.