Temperature Probe Test (Solid State Control); Heating Element Test - Vulcan-Hart VC4EC Service Manual

FULL SIZE ELECTRIC CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
TEMPERATURE PROBE TEST
(SOLID STATE CONTROL)
NOTE: The temperature probe used in conjunction
with the Solid State Temperature control is an RTD
(resistance temperature detector) of the Thermistor
type. As temperature increases the resistance value
decreases.
1. Remove the right side panel as outlined under
COVERS AND PANELS in REMOVAL AND
REPLACEMENT OF PARTS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Place a shielded thermocouple in the geometric
center of the oven cavity and determine the
temperature in the oven cavity.
3. Remove the probe lead wires from the solid
state temperature control.
4. Test the probe with an ohmmeter.
A. If the measured resistance values are
inside the given tolerance then the probe is
functioning properly.
B. If the measured resistance values are
outside the given tolerance then replace
the probe and retest.
1) Check oven for proper operation.
5. Reverse procedure to install.
TEMP (°F) OHMS*
77 90,000
240 4,077
260 3,016
280 2,266
300 1,726
320 1,332
340 1,041
(*) Resistance in ohms ± 10%
F25105 (Rev. A, October 2007)
TEMP (°F) OHMS*
360 822
380 656
400 529
425 424
450 334
475 266
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HEATING ELEMENT TEST

The following steps require power
to be applied to the unit during the test. Use
extreme caution at all times.
1. Turn the power switch ON and set the oven
temperature control to the highest setting.
2. Measure the voltage at the heating element
terminals and verify it against the data plate
voltage.
A. If voltage is incorrect, find the source of the
problem.
B. If voltage is correct, check current draw
(amps) through the heating element lead
wires.
NOTE: This method is preferred over a
resistance check when a clamp on type amp
meter is available.
1) If current draw is correct then heating
element is functioning properly. See
table below for proper values.
2) If current draw is not correct, turn the
power switch OFF and disconnect
the electrical supply to the oven.
a. Replace heating element then
proceed to step 3.
C. If unable to check current draw, a
resistance check may indicate a
malfunctioning element.
1) Turn the power switch OFF and
disconnect the electrical supply to
the oven.
2) Remove the lead wires from the
heating element and check resistance
(ohms). See table below for proper
values.
3. Check for proper operation.
KW PER
VOLTAGE
ELEMENT
208 2
2
240
480 2
1. Values in the table are nominal.
NOTES:
Tolerance is +5/-10%.
2. Voltage values are @ 60HZ.
3. Resistance values (ohms) are @
room temperature.
AMPS PER
ELEMENT
OHMS PER
LEAD
ELEMENT
1 PH 3 PH
60 35 21
52 33 28
15 4 111