Lincoln 1921, 1922 service manual Troubleshooting Guide

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	Check, replace if necessary.
	controls
	Fuse holder	Check, replace if necessary.
	Hi-limit thermostat,	Terminals are normally closed. If open, reset
	Oven cavity	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	Check for 240 VAC supply to the transformer primary. If
	(MODEL 1922 ONLY)	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.

6 DTF – 1920 Series Service Manual