GF83.70-P-3053F Heater Device Overheating, Function

GF83.70-P-3053F Heater Device Overheating, 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 of greater than 72 °C and less than 77 °C the STH heater unit (except model 220) or the STH or HB [ZUH] heater unit (model 220) operates in partial load mode.

2. The STH fuel metering pump or the STH or HB [ZUH] fuel metering pump (Y23) and the combustion air blower (A6m2) operate at a low output and rotational 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.

3. Due to a malfunction, the coolant temperature in the STH heater unit or in the STH or HB [ZUH] heater unit increases to the impermissible temperature value of 105 °C.

4. The internal temperature sensing of the STH control unit or the STH or HB [ZUH] control unit (A6n1) recognizes the overheating and activates for approx. 120 s the heater fault run-on period with subsequent fault interlock.

5. 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) is actuated via CAN-B (CANpump B) with the signal "Blower off".

6. The control and operating unit (N18, N22 or N22/7) switches the blower motor off and switches from stationary heating mode to normal operating mode.

7. At the end of the fault run-on period, the combustion air blower (A6m2) and the circulation pump (A6m1) are switched off. The indicator lamp in the STH switch (N72s12 or S46) goes out. The fault interlock is present, restarting the STH heater unit or the STH or HB [ZUH] heater unit is no longer possible:

The malfunction lockout can be deactivated following the removal of the fault by interrupting the voltage supply (terminal 30). In order to achieve this, activate heating mode with the STH switch (N72s12 or S46), withdraw and after approx. 10 s reinsert the corresponding fuse.

^ Model 203, 209
Fuse 35 in the interior fuse box
^ Model 215, 220
Fuse 41 in right fuse box
^ Model 230
Fuse 56 in the rear fuse and relay module