Test #4: Heat System - Whirlpool WED9500E SERIES Service Manual

COMPONENT TESTING
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or
electrical shock.

TEST #4: Heat System

This test is performed when either of the following situations
occurs:
ü Dryer does not heat
ü Heat will not shut off
This test checks the components making up the heating circuit.
The following items are part of this system:
Part of Heating System
Harness/connection
Heater relay
Thermal cut-off
High limit thermostat
Heat element assembly
Gas valve assembly
Centrifugal switch
Outlet thermistor
Inlet thermistor
Machine control electronics
Console electronics
Gas supply
NOTE: On the gas dryer, the inlet thermistor is located at
the drum inlet vent. Refer to strip circuits on page 3-13 to
diagnose heater system.
Dryer does not heat:
Locate the components using figures 1 and 2 (page 3-3). To
access heater system components, remove the console, top
panel, and front panel.
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For Service Technician Use Only
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ELECTRIC DRYER ONLY:
ü Quick Check: Perform steps under "Service Test Mode",
page 2-5, to test for L1 and L2 line voltage.
¾ If L1 is present, the thermal cutoff is functional.
¾ If L2 is present, the centrifugal switch, high limit
thermostat, and the side of the heater connected to
heater relay 1 are functional.
1. Unplug dryer or disconnect power.
2. Slide the top back, remove the front panel, front
bulkhead, and drum to access thermal components.
3. Check Heaters—on the ACU, use an ohmmeter to
measure the resistance between the violet wire terminal
on heater relay #1 and the violet wire terminal on heater
relay #2.
¾ If the resistance is ≤ 50 Ω, go to step 5.
¾ If an open circuit is detected, go to step 4.
4. Visually check the wire connections between each relay
and their respective heaters. If the connections look good,
check for continuity across each heater (violet wire to
center red wire). Refer to strip circuits on page 3-13.
¾ Replace the heater if it is electrically open.
5. Check Thermal Cut-off—on the ACU, use an ohmmeter to
measure continuity between J9-2 (L1) and the black wire
terminal on heater relay #1. Then, measure continuity
between J9-2 (L1) and the black terminal on heater relay
#2.
¾ If there is continuity, go to step 7.
¾ If an open circuit is detected, go to step 6.
6. Visually check the wire connections between each relay
(black wire) and the thermal cut-off. If the connections
look good, check for continuity across the thermal cut-off.
¾ Replace the thermal cut-off if it is electrically open.
7. Check High Limit Thermostat—visually check the wire
connections from the heaters and centrifugal switch to
the high limit thermostat. If the connections look good,
check for continuity across the high limit thermostat.
¾ Replace the high limit thermostat if it is electrically
open.
8. If no open circuit is detected, remove the J14 connector
from the ACU and measure the outlet thermistor
resistance between J14-3 and J14-6 at the connector.
Refer to "Outlet Thermistor Resistance" table on page
3-14, for temperatures and their associated values.
¾ If the resistance corresponds to the temperature, the
outlet thermistor is good. Go to step 9.
¾ If the thermistor resistance does not agree with the
table, replace the outlet thermistor.
9. If the preceding steps did not correct the problem and L1
and L2 were both detected, replace the ACU. If L2 was not
detected, suspect the centrifugal switch before replacing
the ACU.
10. Reassemble all parts and panels.
11. Plug in dryer or reconnect power.
12. Perform steps under "Service Test Mode", page 2-5, to
verify repair.