AD83.70-P-5001A | Stationary heater (STH) diagnosis, troubleshooting | 13.8.97 |
MODEL 129 as of 1.6.97 with CODE (228) stationary heater
| Stationary heater (STH) diagnosis, advanced information | ||
| Stationary heater unit, location of components | ||
Troubleshooting | |||
Complaint | Possible cause | Note | Remedy |
It is not possible to start the stationary heater unit | Undervoltage Malfunction lock-out due to previous overheating Stationary heater timer (N34) Stationary heater/heater booster control module (A6n1) | Charge battery See Hand-Held Tester (HHT) Check all actual values with HHT | |
Malfunction shut-down at start of heater operation with heater unit run-on (approx. 120 seconds ) of combustion air blower (A6m2) and circulating pump (A6m1) without repeat start. | Glow pin (A6r2) in its flame monitor function Stationary heater/heater booster control module (A6n1) | Check all actual values with HHT | |
Malfunction shut-down at start of heater operation with heater unit run-on (approx. 120 seconds) of combustion air blower (A6m2) and circulating pump (A6m1) after an unsuccessful repeat start initiated automatically. | Stationary heater fuel metering pump (Y23) Combustion air blower (A6m2) Glow pin (A6r2) in its flame monitor function Stationary heater/heater booster control module (A6n1) | Check all actual values with HHT | |
Combustion starts during the preglow time | Remains of fuel in combustion chamber due to unsuccessful attempts at starting Internal leakage in fuel metering pump (Y23) | Allow heater unit to operate for 10 minutes | |
Vehicle heater blower does not operate at a coolant temperature > 30°C | Blower motor (M2) Actuation of air conditioning (automatic) control and operating system | ||
Stationary heater/heater booster unit (A6) does not switch to full load operation despite a requirement for heat | Combustion air blower (A6m2) Stationary heater fuel metering pump (Y23) Stationary heater/heater booster control module (A6n1) | Check all actual values with HHT | |
Despite a requirement for heat, the stationary heater/heater booster unit (A6) goes into the combustion interval within approx. 10 minutes during trouble-free heater mode. | Coolant level or routing of coolant lines Actuation of blower motor (M2) Blower motor (M2) Circulating pump (A6m1) Stationary heater/heater booster control module (A6n1) | Check coolant level, if necessary replenish and/or bleed coolant circuit. Check coolant lines for kinks and pinching Check all actual values with HHT | |
Heat output too low | Setting of vehicle heater Combustion air inlet on stationary heater/heater booster unit (A6) Coolant level or routing of coolant lines Heater circuit thermostat Stationary heater/heater booster control module (A6n1) | Increase temperature setting Check combustion air inlet for contamination and clean if necessary Check coolant level and if necessary replenish and/or bleed coolant circuit. Check coolant lines for kinks and pinching. Check function Check all actual values with HHT | |
Despite a reduced requirement for heat, stationary heater/heater booster unit (A6) is not switched to part load operation or to the combustion interval. | Stationary heater/heater booster control module (A6n1) | Check all actual values with HHT | |
Escape of combustion exhaust gases which are sooty or form dense smoke | Combustion air inlet at stationary heater/heater booster unit (A6) Exhaust emissions value too high Fuel delivery quantity Combustion air blower (A6m2) Stationary heater/heater booster control module (A6n1) | Check combustion air inlet for contamination and if necessary clean Check and adjust exhaust emissions value with HHT Check all actual values with HHT | |
Gray/white combustion exhaust gases (white smoke) | Exhaust emissions value too low | Check and adjust exhaust emissions value with HHT | |
Loss of coolant Gray/white combustion exhaust gases (white smoke) Exhaust gas odor extremely sweet | Stationary heater/heater booster unit (A6) | Check stationary heater/heater booster unit (A6) for external leaks and if necessary replace heater unit. | |
Loss of fuel or fuel odor | Fuel supply of stationary heater unit leaks | Localize leakage point, check fuel metering pump, fuel supply lines, connections and stationary heater unit for fuel leaks and if necessary seal leakage point or replace component | |
Heater operation cannot be terminated manually | Stationary heater timer (N34) | ||
It is not possible to test the stationary heater components with the HHT No communication between HHT and stationary heater/heater booster control module (A6n1) | Cables, cable connections Voltage supply Diagnostic cable | Check and if necessary replace |