Webasto Thermo 350 Service Manual download pdf (Page 38)

6 Functional Checkouts Thermo 230 / 231 / 300 / 301 / 350

604

6.3.5.2 Fuel Pump Check on Heaters with Control Unit

1572D

NOTE

On heaters with control unit 1572D the fuel pump may

only be checked by means of the PC heater diagnosis.

The fuel pump and the fuel hoses must be replaced every

5 years.

6.3.6 Fan Motor Check

NOTE

The fan motor check is performed with the burner

installed. If normal conditions are not obtained the fan

motor must be replaced.

Check

– check fan motor bearing condition(binding)

– measure heater power supply voltage

– switch on heater

– measure speed and compare with the diagram below

Thermo 230/231 4400 ±350 24 Volt

Thermo 300/301 5200 ±420 24 Volt

Thermo 230/301 6200 ±500 24 Volt

6.3.7 Solenoid Valve Check

NOTE

A solenoid valve leaking valve seat shows by rather long

smoke emissions during run-down. In this case fuel keeps

dripping through the fuel nozzle.

Short smoke emissions are normal caused by clearing the

area between solenoid valve and nozzle bore.

Check

CAUTION

Disconnect solenoid valve connector from control unit to

avoid damage to the control unit.

– Check electrics for the following values:

• break voltage 17.0 Volts

• operating voltage 19.2 ... 28.8 Volts

• power consumption at

nominal voltage and 20° C 10 Watts

• nominal current 0.42 Amps

NOTE

With all variants of the control unit the solenoid valve may

also be checked by means of the PC heater diagnosis

(component test).

6.3.8 Nozzle Block Preheater Check

NOTE

At a temperature of < 0° C the heater cartridge in the

nozzle block is activated. The heating period depends on

the heat reflected within the combustion chamber.

Preheating is deactivated when the thermostat ambient

temperature is +8° C.

Power consumption is 130 ±13 Watts at 24 Volt.

Check

– swing burner head open or remove

– disconnect electrical connector

– connect ohmmeter to connector

– using cooling spray cool down thermostat or bridge

– resistance (max. 4.5 Ω).

20 22 24 26

30 32

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

Thermo

350

Thermo

300/301

Thermo

230/231

Voltage

Speed (1/min.)

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 92 93

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Webasto Thermo 350 Service Manual Page 38

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