Whirlpool WET4027HW0, Service Manual

Page: 56 / 82

4-10
n
27” Stacked Laundry Center
TESTING – DRYER
DANGER
Electrical Shock Hazard
Only authorized technicians should perform
diagnostic voltage measurements.
After performing voltage measurements,
disconnect power before servicing.
Failure to follow these instructions can result in
death or electrical shock.
For Service Technician Use Only
TEST #3: Heat System
This test is performed when either of the following situations
occurs:
n
Dryer does not heat
n Heat will not shut off
This test checks the components making up the heating circuit.
Dryer does not heat
Electric dryer: (See Figure 1 below)
1. Unplug dryer or disconnect power.
2. Remove top front and front access panels to access
machine electronics and thermal components.
3. Using an ohmmeter and referring to the wiring diagram,
measure the resistance from timer terminal A to the
terminal at the heater (red/white).
¾
If the resistance is about 10 Ω, go to step 5.
¾ If an open circuit is detected, go to step 4.
4. Visually check the wire connections to the operating
thermostat, thermal cut-off, high limit thermostat, and
heater. If the connections look good, check for continuity
across each of these components.
¾ Replace the heater if it is electrically open.
¾
Replace both the thermal cut-off and high limit
thermostat if either the thermal cut-off or high limit
thermostat is electrically open.
¾
Replace the operating thermostat if it is electrically open.
5. If the preceding steps did not correct the problem and L1
and L2 were both detected, replace the timer.
6. Reassemble all parts and panels.
7. Plug in dryer or reconnect power.
Gas dryer: (See Figure 2, page 4-11))
1. Verify that the gas supply to the dryer is turned on.
2. Unplug dryer or disconnect power.
3. Perform TEST #3a: Thermal Fuse on page 4-11. If the
thermal fuse is OK, go to step 4.
4. Locate the high limit thermostat. Measure the continuity
through it by connecting the meter probes to the red and
black wire terminals.
¾
If there is an open circuit, replace the high limit
thermostat.
¾
Otherwise, go to step 5.
5. Perform TEST #3c: Gas Valve on page 4-12. If the gas valve
is OK, go to step 6.
6. If the preceding steps did not correct the problem,
suspect the centrifugal switch before replacing the timer.
7. Reassemble all parts and panels.
8. Plug in dryer or reconnect power.
Heat will not shut off:
1. Unplug dryer or disconnect power.
2. Remove top front and front access panels to access
machine electronics and thermal components.
3. Check heater coil for a short to ground (usually inside the
heater box). Repair or replace if necessary.
4. Plug in dryer or reconnect power.
5. Run an “AIR” only timed dry cycle (no heat). With a
voltmeter set to AC, connect voltmeter to timer terminals
C and A and measure the voltage across terminals C and A.
¾
If voltage is present (~240 VAC for electric models,
~120 VAC for gas models), heat system is working
normally.
¾
If little or no voltage is present, the heater is activated.
Unplug dryer or disconnect power and replace the timer.
6. Unplug dryer or disconnect power.
7. Reassemble all parts and panels.
8. Plug in dryer or reconnect power.
C — B — A
L1
HEATER STRIP CIRCUIT
BK R
BK
L2
OPERATING
THERMOSTAT
THERMAL
CUTOFF
2M 1M
BK
R
CENTRIFUGAL
SWITCH
TIMER
CONTACTS
HI - LIMIT
THERMOSTAT
HEATER
ELEMENT
R/W
R
R/W
R/W
R
Figure 1 - Electric Dryer Strip Circuit
ELECTRIC DRYER HEATER CIRCUIT