ad8370l5000a

Auxiliary heater (ZHE) diagnosis, troubleshooting

Type ad · topic 83.70 · version 0101 · 2003-06-13

Applies to: MODELS 667, 668, 670 with CODE (H11) Warm air auxiliary heater with CODE (H12) Warm water auxiliary heater with CODE (H14) Heavy duty hot water auxiliary heater

Where it sits

Function group 3 Body › 83 Climate control › 83.70 Auxiliary/supplementary heater — Series 667 · Series 668 · Series 670

AD83.70-L-5000A

Auxiliary heater (ZHE) diagnosis, troubleshooting

7.4.98

MODELS 667, 668, 670
with CODE (H11) Warm air auxiliary heater
with CODE (H12) Warm water auxiliary heater
with CODE (H14) Heavy duty hot water auxiliary heater

Danger!

Risk of explosion due to fuel vapors, risk of poisoning from breathing in combustion gases and risk of injury due to combustions during or after heating operation

Do not operate stationary heater, auxiliary heater or engine with heater booster in closed areas or when refueling. Allow heater unit to cool down after operation and wear protective gloves.

AS83.70-Z-0002-01A

Auxiliary heater (ZHE) diagnosis, previous knowledge

AD83.70-L-2000A

Troubleshooting

Fault

Possible cause

Remedy

Auxiliary heater switch (S16) without function

Discontinuity or short circuit in line from ZHE control module to auxiliary heater switch

Inspect cables, plugs, connectors, fuses and electrical components for damage, correct connection, loose contact and corrosion.

Auxiliary heater switch faulty

Check auxiliary heater switch

Timer

(S110 or S112) without function

Discontinuity or short circuit in lines from ZHE control module to timer

Inspect cables, plugs, connectors, fuses and electrical components for damage, correct connection, loose contact and corrosion.

Timer faulty

Check timer

Heater booster switch (S14) without function

only with D5W heater

Discontinuity or short circuit in lines from ZHE control module to switch (S14)

Inspect cables, plugs, connectors, fuses and electrical components for damage, correct connection, loose contact and corrosion.

Heater booster switch faulty

Check heater booster switch

Soot-producing combustion

Combustion air line, exhaust line blocked

Remove blockage

Fuel metering pump delivers too much

Check fuel metering pump

Deposits in the heat exchanger

Remove deposits

No hot air in the interior

only with hot water heater

Vehicle fan not switched on

Vehicle fan without function

Switch on vehicle fan

Inspect vehicle fan, as well as cables, plugs, connectors, fuses and electrical components for damage, correct connection, loose contact and corrosion.

Diagnosis with STAR DIAGNOSIS not possible

Auxiliary heater not switched on

Switch on auxiliary heater, blower and temperature switch to "max".

Referenced documents