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DTF – 1920 Series Service Manual
6
TROUBLESHOOTING GUIDE
1921 208 VAC 60 HZ. 3 PHASE
1922 240 VAC 60 HZ. 3 PHASE
SYMPTOM POSSIBLE CAUSE EVALUATION
Oven fan will not run Incoming power supply Check circuit breakers. Reset if required. Call power
co. if needed.
Fuses, 10 Amp, motor and
controls
Check, replace if necessary.
Fuse holder Check, replace if necessary.
Hi-limit thermostat,
Oven cavity
Terminals are normally closed. If open, reset
thermostat and retest. If thermostat will not hold for
maximum oven temperature, and oven is not exceeding
temperature setting, check for proper location of
capillary bulb in its spring holder. If the capillary checks
okay, replace the hi-limit thermostat.
Switch, main power Check continuity between switch terminals. Replace
switch as needed.
30 minute time delay relay Check for supply voltage to 30 minute time delay relay
at terminals #1 and #6. If no voltage is present, trace
wiring back to main power switch. If there is supply
voltage at terminals #1 and #6, check for output voltage
at terminals #2 and #3. If there is incoming voltage but
no output voltage, and the main power switch is on,
replace the 30 minute time delay relay.
Relay, main fan Check for supply voltage to relay contacts, if no voltage
is present, trace wiring back to power supply. Check for
supply voltage to the coil of the main fan relay. If no
voltage is present, trace wiring back to the 30 minute
time delay relay. If voltage is present, check to insure
contacts are closing. Replace as needed.
Transformer, Motor
(MODEL 1922 ONLY)
Check for 240 VAC supply to the transformer primary. If
no voltage is present, trace wiring back to relay. If
240VAC is present at transformer primary, check for
208VAC at the transformer secondary. If there is
primary voltage, but no secondary voltage, replace
transformer.
Circuit breaker(s), 3A. Push and reset circuit breakers. Check for voltage to
the circuit breaker. If no voltage is present, trace wiring
back to the main fan relay. If there is voltage present,
proceed. Check for continuity through the circuit
breaker, if the circuit breaker has been reset and there
is no continuity through the circuit breaker, replace the
circuit breaker.
Main fan motor Check for supply voltage at motor. If no voltage is
present, trace wiring back to circuit breakers.
WITH POWER OFF: Check for opens, shorts or
grounds. Turn fan blade to check for locked rotor.
Capacitor Check for shorts or grounds.
WARNING: Capacitor has a stored charge, discharge
before testing.
Oven will not heat Main fan motor Check for main fan operation. If it is not operating, refer
to “Oven fan will not run”.
Air pressure switch This normally open switch should close when the main
fan is activated. Refer to the “Removal and installation”
section for proper adjustment. Replace as needed.