Spheros thermo 231, Workshop Manual

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Thermo 230 / 231 / 300 / 301 / 350 5 Troubleshooting
503
5.3 Fault Symptoms during Functional
Checkouts and Error Code Output or
Tests with Diagnostic Computer,
Components Tester or PC Heater
Diagnosis
5.3.1 General
Error Code Output
NOTE
Only heaters with a control unit 1572D provide an error
code output.
When equipped with a standard timer an error code
readout is available after a malfunction on the display of
the timer.
When the heater is operated by means of a switch a
coded flashing of the operating indicator light during
run-down of the heater or until switch-off indicates the
type of error (see 3.9).
Diagnostic Computer
NOTE
Checks with the diagnostic computer may only be
performed on heaters equipped with control unit 1572.
By use of the diagnostic computer heaters may be
checked in the vehicle. The following tests are available:
• indication of measured values: water temperature,
control unit supply voltage, flame sensor bright/dark.
• indication and erasure of faults stored in the control
unit.
Operation of the diagnostic computer is menu controlled
by means of four push button switches.
For details refer to operating instructions for "Diagnostic
Computer".
Components Tester
NOTE
Checks with the components tester may only be
performed on heaters equipped with control unit 1572.
Using the components tester several types of faults and
component malfunctions may be analyzed in the vehicle.
The test of the individual components with the compo-
nents tester is not intended. Faults like short or open
circuits may be detected with the components tester but
cannot be localized.
For details refer to operating instructions for "Components
Tester".
PC Heater Diagnosis
By use of the PC heater diagnosis heaters (with control
unit 1572 or 1572D) may be tested in the vehicle.
For details refer to operating instructions for "PC Heater
Diagnosis".
Wrong combustion
CO
2
value cannot be set to rated value,
combustion irregular.
• air bubbles in suction line (suction line leaking).
• fuel filter contaminated or leaking.
• fuel system integration leak (suction height, low
pressure in tank); observe installation instructions.
• fuel pump defective (pump pressure).
• return line throttled.
• filter screen in pump contaminated.
• O-ring sealing on fuel pump no longer effective
(ageing)
• nozzle jet defective.
• combustion air or exhaust lines throttled or closed.
• fan motor speed too low.
Fig. 501 General Fault Symptoms (Sheet 3 of 3)
Symptom Probable Cause