PAGE 15
FOR SERVICE TECHNICIAN’S USE ONLY
DO NOT REMOVE OR DESTROY
4. Visually check the wire connections to
the thermal cut-off, high limit thermostat, and
heater. If the connections look good, check for
continuity across each of these components.
Refer to strip circuit on page 22.
Replace the heater if it is electrically open.
Replace both the thermal cut-off and high
limit thermostat if either the thermal cut-off or
the high limit thermostat is electrically open.
5. If no open circuit is detected, remove the
P14 connector from the CCU and measure the
outlet thermistor resistance between P14-3
and P14-6 at the connector. Refer to “Outlet
Thermistor Resistance” table on page 16 for
temperatures and their associated values.
If the resistance corresponds to the temperature,
the outlet thermistor is good. Go to step 6.
If the thermistor resistance does not agree
with the table, replace the outlet thermistor.
6. If the preceding steps did not correct the
problem and L1 and L2 were both detected,
replace the CCU. If L2 was not detected, suspect
the centrifugal switch before replacing the CCU.
7. Reassemble all parts and panels.
8. Plug in dryer or reconnect power.
9. Perform the “Quick DIagnostic Test”
through Service Diagnostics to verify repair.
GAS DRYER ONLY:
1. Verify that the gas supply to the dryer is
turned on.
2. Unplug dryer or disconnect power.
3. Perform TEST #4b: Thermal Fuse on page
17. If the thermal fuse is OK, go to step 4.
4. Perform TEST #4c: Thermal Cut-Off on page
17. If the thermal cut-off is OK, go to step 5.
5. Locate the high limit thermostat (see
figures 20a & 20b, page 14). Measure the
continuity through it by connecting the meter
probes to the red and black wire terminals.
If there is an open circuit, replace both the
high limit thermostat and the thermal cut-off.
Otherwise, go to step 6.
6. Perform TEST #4d: Gas Valve on page
17. If the gas valve is OK, go to step 7.
7. If the preceding steps did not correct
the problem, suspect the centrifugal switch
before replacing the CCU.
8. Reassemble all parts and panels.
9. Plug in dryer or reconnect power.
10. Perform the “Quick Diagnostic Test”
through Service Diagnostics to verify repair.
Heat will not shut off:
ALL DRYERS:
1. Unplug dryer or disconnect power.
2. Remove top panel to access the machine
electronics.
3. Remove connector P14 from the CCU
and measure the resistance between P14-3
and P14-6 at the connector. Refer to “Outlet
Thermistor Resistance” table on page 16 for
temperatures and their associated values.
If the resistance corresponds to the
temperature, the outlet thermistor is good.
If the thermistor resistance does not agree
with the table, replace the outlet thermistor.
4. ELECTRIC DRYER ONLY: Check heater
coil for a short to ground (usually inside the
heater box). Repair or replace if necessary.
5. Plug in dryer or reconnect power.
6. Run an “AIR” only timed dry cycle (no
heat). Check heater relay output on CCU.
With a voltmeter set to AC, measure the voltage
across heater relay terminals 1 and 2.
If voltage is present (~240V AC for electric,
~120V AC for gas), the relay is open and
working normally.
If little or no voltage is present, the relay is
closed and heater is activated. Replace the CCU.
7. Unplug dryer or disconnect power.
8. Reassemble all parts and panels.
9. Plug in dryer or reconnect power.
10. Perform the “Quick Diagnostic Test”
through Service Diagnostics to verify repair.
TEST #4a: Thermistors
NOTE: Refer to strip circuit on page 22 to
diagnose outlet and inlet temperature thermistors.
Outlet (Exhaust) Thermistor
The CCU monitors the exhaust temperature
using the outlet thermistor, and cycles the
heater relay on and off to maintain the desired
temperature. NOTE: Begin with an empty dryer
and a clean lint screen.
3Quick Check: Exhaust thermistor readings
in °F, °C, and resistance are provided
in “Service Diagnostics ➔ Component
Activation ➔ Exhaust Thermistor.”
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