AD83.70-S-3000C | Auxiliary heater (AHE) diagnosis operational check | 19.8.98 |
MODEL 638.0 /1 /2 as of 15.10.97 with CODE (H12) Hot water auxiliary heater
MODEL 638.0 /1 /2 with CODE (HZ5) Hot water auxiliary heater 10 kW with timer
Danger! | Risk of explosion due to fuel vapors, risk of poisoning from combustion gases and risk of injury from burning during or after heater operation | Do not put stationary heater or engine with heater booster into operation in confined spaces or in the vicinity of tank installations. Allow heater unit to cool down after operation and wear protective gloves. | |
Auxiliary heater (AHE) diagnosis, previous knowledge | |||
Auxiliary heater function notes | |||
Function check | |||
Scope of test | Operation / requirement | Specified value | Possible cause/remedy |
1 Switching auxiliary heater on and off via auxiliary heater timer | Blower step 0 Ignition: OFF Temperature selection switch set at maximum Sufficient fuel in tank Press "Immediate heating" button at A7 Press "Immediate heating" button at A7 again | The flame symbol appears in the display, the remaining running time is displayed Auxiliary coolant heater pump is switched on Heater blower step 1 is switched on (from coolant temperature >30°C). When the ignition is OFF the blower always remains on step 1 Heating control of the climate control is brought into operation Water auxiliary heater is turned off Run-on time of the combustion air blower: 120sec. Not available if no fuel has been drawn | |
2 Test function | Auxiliary heater in operation | The temperature of the air must noticeably rise approx. 4 min after the water auxiliary heater is switched on | |
3 Switching auxiliary heater on and off via remote control For models 638.094/194/294 only | Ignition: OFF Switch on the auxiliary heater from outside the vehicle with the remote control (maximum 600 meters) Switch off the auxiliary heater with the remote control (maximum 600 meters) | Remote control indicator lamp must illuminate Heater blower step 1 is switched on Auxiliary coolant heater pump is switched on Auxiliary coolant heater is switched on Heating control of the air climate control is brought into operation Remote control indicator lamp must illuminate Auxiliary coolant heater is switched off Run-on time of the combustion air blower: 120sec. Not available if no fuel has been drawn | |
4 Switching auxiliary coolant heater with heater booster function on and off via climate control pushbutton control unit (A20) For models 638.094/194/294 with codes MQ3, MQ4 and MQ5 only | Engine: RUNNING Sufficient fuel in tank Press heater booster switch (A20s6) on climate control pushbutton control unit Press heater booster switch (A20s6) on climate control pushbutton control unit again |
Display illuminated in air conditioning pushbutton control unit and heater booster switches itself on Display goes out and auxiliary coolant heater with heater booster function switches itself off Running-on of the air blower: 120sec. Not available if no fuel has been drawn |
Referenced documents
- ad8370s200004a Auxiliary heater (AHE), function notes
- ad8370s2000b Auxiliary heater (AHE) diagnosis previous knowledge
- ad8370s600003c Auxiliary heater (AHE) test of electrical system switch-on signal from operating unit
- ad8370s600073a ZHE test of electrical system two-way radio module
- ad8370s600074a ZHE test of electrical system air conditioning on signal from pushbutton control module
- ad8370s6000c Auxiliary heater (AHE) test of electrical system
- as8370z000201a Risk of explosion caused by fuel vapors igniting, risk of poisoning caused by inhaling combustible gases and risk of injury caused by burns during and after operation of heater unit