Stationary heater (STH) diagnosis, function check - AD83.70-P-3003A
MODEL 129 as of 1.6.97 with CODE (228) stationary heater
| Risk of explosion due to fuel vapors, risk of poisoning from inhaling combustion gases and risk of injury from burns during or after heater operation. | Do not put stationary heater, auxiliary heater or engine with heater booster into operation in confined spaces or while refueling. Allow heater unit to cool down after operation and wear safety gloves. | AS83.70-Z-0002-01A | |
| Heater booster unit (STH) diagnosis, advanced information | AD83.70-P-2001A | ||
| Air inlet of heating and ventilation system must be clear, remove any foreign bodies, such as leaves, if necessary. | |||
| The vehicle heater must be set to "MAX" position. | |||
| Check coolant circuit. The coolant circuit must be adequately filled with coolant and bled carefully. Coolant lines must not be kinked or pinched. | |||
| Coolant temperature ≤ 20°C | |||
| Battery voltage 11-14 V | |||
| Function check | |||
| Scope of test | Operation/Requirement | Specified value | Remedy |
| 1 Switch on stationary heater | Press instant heat button |
The green indicator lamp on the timer illuminated, circulating pump and combustion air blower start up; audible operating noise and detectable air flow at exhaust gas outlet Coolant temperature < 59°C Heater circuit thermostat shuts off the entry to the vehicle cooling and heating circuit, and for a more rapid increase in temperature at the heater, initially only permits a short circulation of the coolant which runs from the heater via the heater unit and recirculating pump. |
AD83.70-P-4002A AD83.70-P-5001A |
| 2 Fuel delivery starts after approx. 40 seconds and combustion air blower is switched off for 3 seconds | Fuel metering pump cycles audibly | AD83.70-P-4002A AD83.70-P-5001A |
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| 3 The combustion air blower is switched on again and the cycling frequency of the fuel metering pump is reduced simultaneously | Operating noise of combustion air blower and slower cycling noise of the fuel metering pump is audible | AD83.70-P-4002A AD83.70-P-5001A |
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| 4 The speed of the combustion air blower is increased in 2 stages within 120 seconds, combustion starts and fuel delivery is increased | Audible increase in combustion air blower speed and cycling noise of fuel metering pump and exhaust gas flow heats up detectably at the same time | AD83.70-P-4002A AD83.70-P-5001A |
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| 5 Combustion starts and stabilizes | The combustion air blower and fuel metering pump deliver audibly at their maximum speed or output in full load operation, coolant temperature increases. Coolant temperature in cooling and heating circuit > 30°C : The vehicle heater blower starts up; audible operating noise and detectably warmer air flow in interior Coolant temperature exceeds 59°C : Heating circuit thermostat opens up the path for the coolant flow to the vehicle's cooling and heating circuit, heat exchange starts in the heating heat exchanger for heating up the interior |
AD83.70-P-4002A AD83.70-P-5001A |
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| 6 Switching off stationary heater | Press instant heat button |
The green indicator lamp on the timer goes out, the vehicle heater blower and fuel metering pump are switched off immediately. The air flow in the interior is no longer detectable and the cycling noise of the fuel metering pump is no longer audible. | AD83.70-P-4002A AD83.70-P-5001A |
| 7 Heater unit run-on starts | From part-load operation → Run-on for approx. 110 seconds From pull-load operation → Run-on for approx. 175 seconds |
Circulating pump and combustion air blower continue operating; audible operating noise and air flow, which is slowly cooling down detectably, at exhaust gas outlet | AD83.70-P-4002A AD83.70-P-5001A |
| 8 Run-on terminates | Operating noise of circulating pump and combustion air blower no longer audible, detectable lack of air flow at exhaust gas outlet | AD83.70-P-4002A AD83.70-P-5001A |