Vulcan-Hart 126172, Service Manual

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ELECTRIC COMBI OVENS - TROUBLESHOOTING
SYMPTOM POSSIBLE CAUSES
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No steam generation but cavity fan
operates. 1. Cavity temperature is above steam temperature set point
and oven is performing automatic cooling before steam
generation can start.
2. Water supply off.
3. Steam generator thermal fuse(s) open.
4. Steam generator heating element(s) malfunction.
5. Contactor(s) malfunction. See “HEATING MODE AND
CAVITY FAN SPEEDS” under “ELECTRICAL
OPERATION”.
6. Lime scale build up (moist) on water level sensors giving
false reading. See note at the beginning of
troubleshooting section.
7. Oven control board malfunction.
Oven displays “888F” or “888C” in the
temperature display. 1. Cavity temperature probe.
NOTE: On 10 level machines - error in the single cavity
temperature probe. On 20 level machines - error in the
upper cavity temperature probe.
A.
Damaged probe or thermocouple lead wire open.
B. Board connection loose or connector not inserted
onto board properly (mis-aligned).
C. Thermocouple lead wires reversed. When heating,
cavity temperature will appear to decrease for
several seconds, then error code will display.
2. Low or no voltage on battery backup to maintain controls
setup and program information in SRAM. See “BATTERY
BACKUP - PROGRAMMABLE CONTROL” under
“SERVICE PROCEDURES AND ADJUSTMENTS”.
3. Incorrect temperature probe in use. Ensure the
temperature probe is not a thermistor type by checking its
resistance. If resistance measures approximately 110
ohms at 70-80°F then do not use.)
Oven displays “999F" or “999C" in the
temperature display. 1. Cavity temperature probe.
NOTE: On 10 level machines - error in the single cavity
temperature probe. On 20 level machines - error in the
lower cavity temperature probe.
A.
Damaged probe or thermocouple lead wire open.
B. Board connection loose or connector not inserted
onto board properly (mis-aligned).
C. Thermocouple lead wires reversed. When heating,
cavity temperature will appear to decrease for
several seconds, then error code will display.
2. Low or no voltage on battery backup to maintain controls
setup and program information in SRAM. See “BATTERY
BACKUP - PROGRAMMABLE CONTROL” under
“SERVICE PROCEDURES AND ADJUSTMENTS”.
3. Incorrect temperature probe in use. Ensure the
temperature probe is not a thermistor type by checking its
resistance. If resistance measures approximately 110
ohms at 70-80°F then do not use.)