Lincoln 1100 Series Service Manual page 25

No control box cooling
No automatic control
Control box cooling fan
continues to run
Oven will not heat
Impinger II –1100 Series Service Manual - Domestic
Oven Start Relay
Cooling Fan Motor(s)
Thermostat, Cooling
Cooling Fan Motor(s)
Thermostat, Cooling Fan
Main Fan Motor
Heat Switch
Air Pressure Switch
Fuse, 3 Amp
Fuseholder
Temperature Control
Thermocouple Probe
Temperature Control
Potentiometer
Mercury Contactor
Heater Elements
Check for main fan operation. If not operating, refer to
"Oven Fan Will Not Run".
Check relay contacts. 120 VAC should be present.
120 VAC should be present at the fan motor. If voltage
is present, check for opens or shorts. WITH POWER
OFF: Check for locked rotor of the fan motor.
Check the cooling fan thermostat. box cooling Fan
(Thermostat closes at 120°F and opens at 100° F.).
With the cooling fan thermostat pre-heated, check for
continuity. If switch is open, replace.
120 VAC should be present at the fan motor. If voltage
is present, check for opens or shorts. WITH POWER
OFF: check for locked rotor of the fan motor.
This normally open thermostat should close at 120° F
(48.9° C) and reopen at 100° F (37.8° C).
Check for main fan operation. If it is not operating,
refer to "Oven fan will not run".
With switch on, check for 120 VAC on both terminals
to neutral. Replace if defective.
This normally open switch should close when the main
fan is activated. Adjust if necessary (Refer to page
23). Replace if defective.
Check, replace if necessary
Check, replace if necessary
Check for 120 VAC supply at terminal #11 to neutral
on temperature control. If no voltage is present, trace
wiring back to 3-amp fuse. Turn the temperature
adjustment knob to maximum temperature position
and check for 120 VAC at the load terminal (#9) and
neutral. If 120 VAC is present and unit is not heating,
refer to "Mercury Contactor" for next check. If 120
VAC is not present, proceed.
WITH POWER ON AND THERMOCOUPLE LEADS
ATTACHED TO THE TEMPERATURE CONTROL
BOARD: measure D. C. millivolt output of these leads.
Refer to thermocouple chart on page 36 for proper
readings. If these readings are not achieved, replace
thermocouple.
WITH POWER OFF: remove the potentiometer leads
from the temperature control board and measure
ohms from black to white leads. The reading should
be from approximately 0 to 2.5k ohms as the dial of
the potentiometer is turned throughout its full rotation.
From black to red leads, the reading should be
approximately 2.5k ohms (constant) throughout the full
rotation of the dial. If these readings are not achieved,
replace the potentiometer. If the thermocouple probe
and the control potentiometer check good, then the
problem is usually with the temperature control board.
Check for 120 VAC to the contactor coil. If voltage is
present and the contactor will not activate, replace the
contactor. Also, check each contactor for proper high
voltage input and output.
Check the Amp. draw on each hot leg for proper load.
Check the specifications plate for rating information. If
the Amp. draw is low or high, check the individual
elements for opens, shorts, and proper resistance.
WITH POWER OFF: To check resistance of the
elements, remove all leads from the elements and use
an accurate digital VOM. The element resistance
should be as follows: 208V - 27 ohms approximately
25