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Test #4: Heat System
This test is performed when either of the following situations
occurs:
•
Dryer does not heat
•
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
Heater element assembly
Inlet thermistor
NTC air channel
Thermal fuse
Machine control electronics
Test #4a: Heater Element (Condenser Dryer)
Heater does not heat:
Quick Check: Perform Test #1: ACU Power Check,
Test #2: Supply Connections,
voltage.
1. Unplug dryer or disconnect power.
2. Remove top panel, right side panel, and console to access
ACU and remove back blower/heater cover to access
thermal components.
3. Check for any loose connections, harness in bad condition,
or short to ground on any metal terminal. Repair or replace
if necessary.
4. In the back panel disconnect one side of the connectors to
the thermo-fuses and Hot Side NTC so that the heater can
be checked. Use an ohmmeter to measure the resistance of
the wires.
n If the resistance between the Brown and Orange Wires
is ≤ 50 Ohms, and resistance between the White and
Orange Wires is ≤ 50 Ohms, Go to Step 5.
n Replace the heater if it is electrically open.
5. Check the wire connections between the heater and the
ACU connection CN04.
n Repair or replace as needed.
6. If no open circuit is detected, refer to "Thermistor
Resistance" table on page 3-7 and NTC Air Channel section
of Test #4b: Thermistors on
their associated values.
n If the resistance corresponds to the temperature, the
thermistor is good. Go to step 7.
n If the thermistor resistance does not agree with the
table, replace the thermistor.
7. If no issue is detected with the thermistor, then test each
thermo-fuse for continuity.
8. If the preceding steps did not correct the problem and L1
and L2 were both detected, replace the ACU.
9. Reassemble all parts and panels.
10. Plug in dryer or reconnect power.
11. Perform the Service Test Cycle on
For Service Technician Use Only
Condenser Dryer
page
3-5, and
page
3-5, to test for L1 and L2 line
page 3-7
for temperatures and
page 2-4
to verify repair.
COMPONENT TESTING (Cont.)
Heater will not shut off:
1. Unplug dryer or disconnect power.
2. Remove top panel, right side panel, and console to access
the machine electronics.
3. Refer to "Thermistor Resistance" table on
Air Channel section of Test #4b: Thermistors on
temperatures and their associated values.
n If the resistance corresponds to the temperature, the
outlet thermistor is good.
n If the thermistor resistance does not agree with the
table, replace the outlet thermistor.
4. 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. Perform the Service Test Cycle. Check heater relay output
on ACU. Unplug dryer or disconnect power. With a
voltmeter set to AC, connect voltmeter to CN04 terminals
1 and 2 for heater relay. Plug in dryer or reconnect power.
Measure the voltage across terminals 1 and 2 for heater
relay.
n If voltage is present (~240 VAC), the relay is open and
working normally.
n If little or no voltage is present, the relay is closed and
heater is activated. Unplug dryer or disconnect power
and replace the ACU.
7. Unplug dryer or disconnect power.
8. Reassemble all parts and panels.
9. Plug in dryer or reconnect power.
10. Perform the Service Test Cycle on
Test #4b: Thermistors
Inlet Thermistor (Condenser Dryer, Inside Heater Module)
The ACU monitors the Heater temperature using the inlet
thermistor, and cycles the heater relay on and off, depending on
strategy, to maintain the desired temperature.
NOTE: Begin with an empty dryer at ambient temperature and a
clean lint screen.
1. Unplug dryer or disconnect power.
2. Remove top panel, left side panel, rear fan scroll and
console to access the machine electronics.
3. Remove connect CN15 and check the resistance between
connectors 5 and 6. The following table gives temperatures
and their associated resistance values for a good thermistor.
NOTE: All thermistor resistance measurements must be made
while dryer is unplugged and connector removed from ACU.
Inlet Thermistor Resistance
Temperature
Resistance
°F (°C)
k ohms
32° (0°)
38.417
77° (25°)
12.000
140° (60°)
158° (70°)
203° (95°)
212° (100°)
230° (110°)
266° (130°)
356° (180°)
Whirlpool
24" Compact Condensing Dryer
®
page 3-7
page 3-7
page 2-4
to verify repair.
Resistance Tolerance
(%)
± 7.3
± 5.5
3.043
± 3.4
2.153
± 2.9
0.971
± 1.7
0.837
± 1.5
0.630
± 1.0
0.370
± 1.8
0.116
± 3.4
and NTC
for
3-7
n
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Troubleshooting
