Troubleshooting guide

PAGE 15
FOR SERVICE TECHNICIAN’S USE ONLY
DO NOT REMOVE OR DESTROY
8. If no open circuit is detected, remove P14
from the CCU and measure the outlet thermistor
resistance between P14-3 and P14-6 at the
connector.
If 5–15 k ohms are measured, go to step 9.
If the resistance is less than 1 k, replace
the outlet thermistor.
9. 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.
10. Reassemble all parts and panels.
11. Plug in dryer or reconnect power.
12. Perform steps under “Install Diagnostics”,
page 5, to verify repair.
GAS DRYER ONLY:
1. Verify 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
figure 11b, 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 steps under “Install Diagnostics”,
page 5, 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.
If 5–15 k ohms are measured, the outlet
thermistor is OK.
If the resistance is less than 1 k, replace
the thermistor; if open, repair as necessary.
4. Check heater coil(s) 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(s) on CCU.
With a voltmeter set to AC, measure the
voltage across terminals 1 & 2 for heater
relay #1. If equipped, repeat procedure
with heater relay #2.
If voltage is present (~240VAC for electric,
~120VAC 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 steps under “Install Diagnostics”,
page 5, to verify repair.
TEST #4a: Thermistors
NOTE: Refer to strip circuit on page 21
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.
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. The following
table on page 16 gives temperatures and their
associated resistance values.