512
Thermo G
5 Troubleshooting
5.5.6 Fan and combustion air intake line visual
inspection
1. Inspect a possibly available combustion air intake line
for contamination, condition and deposits.
2. Remove burner head (see 8.4).
3. Separate mixing chamber and fan housing (see 8.5).
4. Remove fan wheel (see 8.8).
5. Inspect fan wheel for damages, the channels of the
fan wheel for contamination and deposits.
6. Install fan wheel (see 8.7).
In the course of this check circlip for proper fit.
7. Check the combustion air fan for smoothness.
8. Install mixing chamber to the fan housing (see 8.5).
9. Install burner head (see 8.4).
5.5.7 Burner motor inspection
The motor can be checked by applying 24V DC voltage.
During that the electrical connection to the control unit
must be disconnected.
1. Remove burner head (see 8.4).
2. Separate mixing chamber and fan housing (see 8.5).
3. Inspect the motor for bearing conditions (stiffness).
4. Disconnect motor plug from the control unit.
5. Check motor with 24VDC (Pin 1 to 24V+).
6. Reconnect motor plug to the control unit.
7. Install mixing chamber to the fan housing (see 8.5).
8. Install burner head (see 8.4).
5.5.8 ZF module inspection
NOTE:
It can only be verified by visual inspection of the igni-tion
electrode, whether the ignition spark jumps over to the
ignition electrode.
High voltage: The voltage received by the ignition
electrode is >13,000 Volt.
During operation or testing of the electronic ignition
unit, the ignition electrode may not be contacted by
persons or items.
Check with STT diagnosis adapter
1. Remove burner head (see 8.4).
2. Connect the test plug instead of the temperature
sensor plug to the control unit.
3. Reconnect the heater to the vehicle electrical system.
4. Connect the SST diagnosis adapter to the heater and
a PC via the interface on the control unit.
5. Start SST diagnosis, establish connection to the
heater and open the Component Test menu.
6. Select the ZF module in the Component Test menu,
enter a runtime and start the component test.
7. Nominal condition: Ignition sparks at the ignition
electrode jump over with a rate of 6Hz.
8. After the test is completed, exit SST diagnosis as
needed.
Fig. 502
Pin 1 & 3
Pin 2 & 3
Overheat protection
Water temperature
sensor
Risc of electric shock!
Warning!
