Vulcan-Hart 126172, Service Manual

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ELECTRIC COMBI OVENS - TROUBLESHOOTING
Page 63 of 68
TROUBLESHOOTING
WARNING: CERTAIN PROCEDURES IN THIS SECTION REQUIRE ELECTRICAL TEST OR
MEASUREMENTS WHILE POWER IS APPLIED TO THE MACHINE. EXERCISE EXTREME CAUTION AT ALL
TIMES. IF TEST POINTS ARE NOT EASILY ACCESSIBLE, DISCONNECT POWER, ATTACH TEST
EQUIPMENT AND REAPPLY POWER TO TEST.
Before performing any of the troubleshooting checks listed below, run the oven control in “DIAGNOSTIC
TEST MODE” for the oven control in use, as outlined under “SERVICE PROCEDURES AND
ADJUSTMENTS”. By utilizing the oven controls “diagnostic test mode” the Service Technician can
quickly and easily determine if a component is functioning properly or in need of repair. The “diagnostic
test mode” can be entered only when the machine is OFF. If the oven is inoperative, then refer to the
troubleshooting guide under SYMPTOM - “Oven inoperative and displays are blank” and/or SYMPTOM -
“Button(s) on keypad inoperative”. Also, check the Technical Service Bulletins for changes to the oven
and for software revisions to the oven control.
NOTE: An accumulation of lime scale on the water level sensors may cause false water level readings to the
oven control. Lime scale that is dry can prevent the sensor from detecting the water level until the lime becomes
moist enough to conduct the electrical signal. This condition can cause water errors and/or overfilling of the
steam generator. In reverse, lime scale that retains water may already be moist enough to conduct the electrical
signal. This condition can cause water errors, prevent the steam generator from filling and cause dry firing of the
heating elements. Subsequently, the steam generators thermal fuse(s) would open to protect the oven. See
“CLEAN CYCLE MODE - STEAM GENERATOR DELIMING” under “SERVICE PROCEDURES AND
ADJUSTMENTS”.
SYMPTOM POSSIBLE CAUSES
Water error light on, buzzer sounds for one
minute and steam generator light comes on
in a cooking mode. 1. Time to fill steam generator has exceeded 4 minutes 20
seconds.
A.
Ensure water supply is on.
B. Check water fill line for clogs.
2. Water too soft for water level sensors to conduct
electricity.
3. Lime scale build up (dry) on water level sensors giving a
false reading to the oven control. See note at the
beginning of troubleshooting section.
Water error light on and buzzer sounds after
steam generator drains. 1. Water still in steam generator - check for clogged steam
generator drain line or drain pump malfunction.
2. Lime scale build up (moist) on water level sensors giving
false reading. See note at the beginning of
troubleshooting section.
Water error light on and buzzer sounds
when oven is turned on. 1. Water still in steam generator - check for clogged steam
generator drain line or drain pump malfunction.
2. Lime scale build up (moist) on water level sensors giving
false reading. See note at the beginning of
troubleshooting section.
Steam generation stops, water error light
and steam generator light on in steam
mode. 1. Oven control board has not seen a call for water request
within 5 minutes powering on. A boil down situation is
assumed.
A.
Lime scale build up on water level sensors giving
false reading. See note at the beginning of
troubleshooting section.
B. Oven control board malfunction.