GF83.70-P-3065B Fault In Coolant Temperature Sensing, Function

GF83.70-P-3065B Fault In Coolant Temperature Sensing, 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. At a coolant temperature over 65 °C and under 77 °C the STH heater unit (except model 220) or the STH or HB [ZUH] heater unit (model 220) operates either in partial load or full load temperature mode, depending on the heat requirement. The STH fuel metering pump or the STH or HB [ZUH] fuel metering pump (Y23) and the combustion air blower (A6m2) deliver at low or maximum output and speed.
The circulation pump (A6m1) delivers the coolant via the heat exchanger (2) and the heating and cooling circuits. The blower motor feeds preheated air into the interior.

2. The STH control unit or the STH or HB [ZUH] control unit (A6n1) continuously monitors the internal coolant temperature sensing.

3. The STH control unit or the STH or HB [ZUH] control unit (A6n1) detects any malfunction of the coolant temperature sensing if the temperature signal exceeds the temperature mode, sensing range.

4. In order to protect the STH heater unit or the STH or HB [ZUH] heater unit, the STH control unit or the STH or HB [ZUH] control unit (A6n1) actuates the heater unit fault run-on for approx. 120 s, this is then followed by a fault shutoff. The STH fuel metering pump or the STH or HB [ZUH] fuel metering pump (Y23) is switched off and the control and operating unit (N18, N22 or N22/7) actuated with the "blower Off" signal over CAN-B (CAN- B).

5. The control and operating unit (N18, N22 or N22/7) switches off the blower motor and changes from the stationary heater mode to standard operating mode.

6. Fault shutoff is terminated.
The combustion air blower (A6m2) and the recirculation pump (A6m1) are switched off. The indicator lamp in the STH switch (N72s12 or S46) is off. Malfunction shutoff is present.

To restart the heater after the fault has been rectified, the STH heater unit (except model 220) or the STH or HB [ZUH] heater unit (model 220) has to be switched off and then on again using the STH switch (N72s12 or S46).