Webasto DBW 2010 Workshop Manual page 27

5 Troubleshooting
Error symptom
Malfunction in water system
Heater shuts off, as heat exchangers (heater and vehicle) do
not give off sufficient heat.
Approximate determination of flow rate
Flow rate in [l/h] =
Malfunction in fuel supply
No fuel delivered to heater.
Malfunction in combustion
CO value cannot be set to nominal value.
2
Combustion irregular.
502
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Heating capacity [kW] as per type label
Temperature difference ΔT in [K] or [°C] measured
between water inlet and outlet on heater (e.g. with
contact thermometer)
Fig. 501 General error symptoms (Section 2 of 2)
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Possible cause
Flow rate insufficient, as
• air or gas in heater, in heat exchangers or in system
sections.
• valves (flow controller) throttled, soiled or closed.
• impurities in system, e.g. filter or with bottlenecks.
• delivery capacity of circulation pump insufficient (air or
gas in pump casing), rotating direction incorrect – check
polarity.
• insufficient frost protection.
• system resistance too high (especially high at low
temperatures).
• circulation pump defective.
Vehicle's heat exchangers (water/air) give off insufficient
heat, as
• air or gas in heat exchangers or in system sections.
• soiled heat exchanger surfaces /(inside/outside).
• insufficient air inlet or air outlet.
• fan: delivery capacity insufficient/rotating direction
incorrect/resistance too high.
• percentage of antifreeze too high.
• heat exchanger too small.
• Fuel tank empty.
• Kinked, sealed-off, clogged or leaky lines.
• Paraffin precipitation or frozen water inclusions in fuel
filter and/or lines.
• Ventilation opening in tank closed.
• Fuel line interchanged.
• Fuel filter soiled.
• Air bubbles in intake line (intake line leaky).
• Fuel filter soiled or leaky.
• Fuel connection leaky (suction height, vacuum in tank);
see installation instructions.
• Fuel pump defective (pump pressure).
• Return line constricted.
• Screen in pump soiled.
• Atomiser nozzle defective.
• Combustion-air and exhaust lines constricted or closed
off.
• Motor speed of combustion motor insufficient.
DBW 2010 / 2016
x 860