Fuel Operated Heater Description and Operation
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Fuel Operated Heater Description and Operation
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The radio remote control has an easy control structure. The radio remote control can be used to set all functions, change them as necessary, preprogram times and read or clear DTCs. With direct visual contact, the radio remote control has an outdoor range of up to 1000 m (3280 ft). External interference, local conditions and dense building development in the surrounding area shorten the range. The radio remote control should always be pointed towards the vehicle when activated for data transmission. If the radio remote control is out of range, the preset mode is then available as an alternative.
The parking heater work independently of the engine and thus offer a double plus: preheating the vehicle passenger compartment and the engine. The parking heater is integrated in the water cooling system of the engine. The thermal energy gained is absorbed by the vehicles own heat exchanger and distributed into the interior through their existing air vents. The engine is warmed up with the residual heat in the water cooling system of the engine.
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Preheating Mode, Switching On
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When the parking heater is switched on, the water pump starts up. After that the combustion air fan, glow plug and fuel dosing pump starts the combustion procedure according to a certain program, with pre-rinsing and preheating. Once a stable flame has formed, the time control switches the glow plug off.
Depending on the heat requirements the parking heater is controlled in the stages: HIGH, ECO, OFF (control pause). The temperature thresholds are permanently programmed in the parking heater control module. If the cooling water temperature reaches 85°C (185°F) in the ECO stage, the parking heater control module switches to the control pause. This is followed by approx. 130 s after running. The operating display is still on and the water pump also continues to run during the control pause.
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Preventing With Changeover Switch Heating/Venting
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Preventing means triggering the vehicle fan directly by the heater preselection timer or, even more possible, by a remote control bypassing the heater. In this way in summer months when the insides of a vehicle get heated up when standing in the sunshine, it is possible to allow fresh air to vent the vehicle.
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Control and Safety Features
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If the parking heater fails to ignite within 90 s after the parking heater fuel pump starts, the start procedure is repeated as described. After a further 90 s of fuel pumping and the parking heater still fails to ignite again, the parking heater is switched off in a fault mode. The controller is locked after a certain number of failed starts. For fault displaying and clearing refer to
Fuel Operated Heater Diagnostic Trouble Code (DTC) Displaying and Clearing
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If the flame is cut off during operation, a new start is activated. If the parking heater fails to ignite within 90 s after fuel pumping has started again, or ignites but does not run again within 15 min, the heater is switched off in a fault mode. The fault mode can be cancelled by switching off and on again. Do not repeat this procedure more than 2 times.
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If the parking heater is overheated (lack of water, poorly vented cooling circuit), the parking heater overheat sensor triggers, the fuel supply is interrupted and the parking heater is switched off. A DTC is set. Once the cause of overheating has been eliminated, the parking heater can be switched on again by switching off and on again (on condition that the parking heater has cooled down sufficiently, cooling water temperature less than 70°C (158°F)). The controller is locked after a certain number of overheating shutdowns. For fault displaying and clearing refer to
Fuel Operated Heater Diagnostic Trouble Code (DTC) Displaying and Clearing
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The parking heater is switched off in fault mode if the lower or upper voltage limit is reached.
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The parking heater does not start when the glow plug is defect or electrical lead to the dosing pump is interrupted.
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The fan motor speed is monitored continuously. If the fan motor does not start up, is blocked or if the speed falls below 40% of the nominal speed, the parking heater is switched off in fault mode after 60 s.
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