Service Manual

3-14
n
Whirlpool & Maytag Front-Load Dryers
COMPONENT TESTING
For Service Technician Use Only
TEST #4: Heat System
This test is performed when either of the following situaons
occurs:
ü Dryer does not heat
ü Heat will not shut o
This test checks the components making up the heang circuit.
The following items are part of this system:
Part of Heang System Electric Dryer Gas Dryer
Harness/connecon
ü ü
Heater relay
ü ü
Thermal cut-o
ü ü
High limit thermostat
ü ü
Heat element assembly
ü
no
Gas valve assembly no
ü
Centrifugal switch
ü ü
Outlet thermistor
ü ü
Inlet thermistor
ü ü
ACU
ü ü
Console electronics
ü ü
Gas supply no
ü
NOTE: On the gas dryer, the inlet thermistor is located at
the drum inlet vent. Refer to strip circuits on page 3-15 to
diagnose heater system.
Dryer does not heat:
Locate the components using gures 1 and 2 on this page.
To access heater system components, remove top and front
panels.
ELECTRIC DRYER ONLY:
ü
Quick Check: Perform steps under “Service Diagnosc
Mode”, page 2-4, to test for L1 and L2 line voltage.
¾ If L1 is present, the heater relay is receiving L1 line
voltage.
¾ If L2 is present, the heater relay is receiving L2 line
voltage, conrming that the centrifugal switch, heater,
high limit thermostat, and the thermal cut-o are
funconal.
1. Unplug dryer or disconnect power.
2. Remove front panel to access thermal components.
3. Using an ohmmeter and referring to the strip circuit or
wiring diagram, measure the resistance from the red wire
terminal at the thermal cut-o to the red/white wire
terminal at the heater.
¾ If the resistance is about 10 Ω, go to step 5.
¾ If an open circuit is detected, go to step 4.
3$*(
FOR SERVICE TECHNICIAN’S USE ONLY
DO NOT REMOVE OR DESTROY
1. Unplug dryer or disconnect power.
2. Slide the top back, remove the front panel,
front bulkhead, and drum to access thermal
components.
3. Check Heaters—on the ACU, use an
ohmmeter to measure the resistance between
the violet wire terminal on heater relay #1
and the violet wire terminal on heater relay #2.
¾If the resistance is ) 50 1, go to step 5.
¾If an open circuit is detected, go to step 4.
Figure 10b - Thermal components,
gas dryer, viewed from front.
Outlet
Thermistor
Thermal Fuse
Gas Dryer
Thermal
Cut-Off
High Limit Thermostat
Flame
Sensor
4. Visually check the wire connections between
each relay and their respective heaters. If the
connections look good, check for continuity
across each heater (violet wire to center red
wire). Refer to strip circuit on page 25.
¾Replace the heater if it is electrically open.
5. Check Thermal Cut-off—on the ACU, use
an ohmmeter to measure continuity between
J9-2 (L1) and the black wire terminal on heater
relay #1. Then, measure continuity between J9-2
(L1) and the black terminal on heater relay #2.
¾If there is continuity, go to step 7.
¾If an open circuit is detected, go to step 6.
6. Visually check the wire connections
between each relay (black wire) and the
thermal cut-off. If the connections look good,
check for continuity across the thermal cut-off.
¾Replace the thermal cut-off if it is
electrically open.
7. Check High Limit Thermostat—visually
check the wire connections from the heaters
and centrifugal switch to the high limit
thermostat. If the connections look good, check
for continuity across the high limit thermostat.
¾Replace the high limit thermostat if it is
electrically open.
Figure 10a - Thermal components,
electric dryer, viewed from front.
Inlet Thermistor/High Limit
Thermostat Assembly
Heater
Element
Electric Dryer
Thermal Fuse
Outlet
Thermistor
Thermal
Cut-Off
Figure 1 - Thermal components, electric dryer, viewed from front.
3$*(
FOR SERVICE TECHNICIAN’S USE ONLY
DO NOT REMOVE OR DESTROY
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 1, go to step 5.
¾If an open circuit is detected, go to step 4.
Figure 10b - Thermal components,
gas dryer, viewed from front.
Outlet
Thermistor
Thermal Fuse
Gas Dryer
Thermal
Cut-Off
High Limit Thermostat
Flame
Sensor
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 circuit on page 25.
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.
Figure 10a - Thermal components,
electric dryer, viewed from front.
Inlet Thermistor/High Limit
Thermostat Assembly
Heater
Element
Electric Dryer
Thermal Fuse
Outlet
Thermistor
Thermal
Cut-Off
Figure 2 - Thermal components, gas dryer, viewed from front.
4. Visually check the wire connecons to the thermal cut-
o, high limit thermostat, and heater. If the connecons
look good, check for connuity across each of these
components. Refer to strip circuit on page 3-15.
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Failure to do so can result in death or
electrical shock.
Replace all parts and panels before operating.