Test #4C Thermistor (Set2) - Whirlpool 4.3 CU FT Service Manual

This test is used to determine if power is
present at the machine control electronics.
This test assumes that proper voltage is
present at the outlet.
1. Unplug dryer or disconnect power.
2. Check for appropriate line voltages at the
WARNING
outlet: 240VAC (electric 2-phase) or 208VAC
(electric 3-phase).
If line voltage is present, go to step 3.
If line voltage is not present, check for
tripped circuit breaker or blown household
fuse. If CB (circuit breaker) is not tripped,
Electrical Shock Hazard
have customer check with qualified
Disconnect power before servicing.
electrician.
Replace all parts and panels before operating.
3. Remove top panel, left side panel, and
Failure to do so can result in death or
console to access the machine electronics.
electrical shock.
4. ACU VAC – With voltmeter set to AC,
connect black probe to ACU J13-2 (L2) and
red probe to J13-1 (L1). (See Figure 2.)

TEST #4c Thermistor (SET2)

Plug in dryer or reconnect power.
Compressor Thermistor (NTC SYSTEM)
M – Motor Supply
NOTE: Begin with an empty dryer at ambient temperature and
J4-1 L1 Motor
a clean lint screen.
J4-2 L2 Motor
1. Unplug dryer or disconnect power.
FM – Fan
2. Remove top panel, left side panel, and console to access
J2-1 L1
the machine electronics.
J2-3 L2
3. Remove connector J6 (HP dryer) from the ACU and
measure the resistance between J6-1 and J6-3 at the
DP – Drain Pump
J3-1 L1
J3-3 L2
CONNECTOR LOCATION (ACU TOP)
WI1 – MCU communication
WI2 – User
interface
THERMISTOR (NTC)
DP – Drain
pump
ACU
FM – Fan
M – Motor
supply
Figure 2 - ACU Connectors
& Pinouts
For Service Technician Use Only
WI2 – User Interface
J17-1 VPOS
J17-2 +5VDC
J17-3 WIDE
J17-4 GND
SEH – Moisture Sensor
J11-1 Gnd
J11-3 Moisture Sensor
IF – RFI
J13-1 L1
J13-2 L2
HX-SLE
Figure 1 - Thermistor Connector (SET2)
BU
J6-1
Figure 3 - Thermistor Strip Circuit
connect black probe to ACU J17-4 (ground)
and red probe to J17-2 (+5VDC). Plug in
dryer or reconnect power.
If +5VDC is present, unplug dryer or
disconnect power and go to step 8.
If +5VDC is not present, go to step 6.
connector. The following table gives temperatures and
6. Unplug dryer or disconnect power. Unplug
their associated resistance values.
J7 and J6 from the ACU. Plug in dryer or NOTE: All thermistor resistance measurements must be
made while dryer is unplugged and connector removed
reconnect power and repeat step 5.
from ACU.
If +5VDC returns, one of the thermistors ¾ If the resistance is OK, the compressor thermistor is
good. Proceed to step 4.
has shorted. To diagnose thermistors,
¾ If the thermistor resistance does not agree with the
see TEST #4c, page 17.
table, replace the compressor thermistor.
If +5VDC is not present, go to step 7.
COMPRESSOR THERMISTOR RESISTANCE
7. Unplug dryer or disconnect power.
TEMPERATURE
Reconnect J7 and J6 to the ACU and unplug
°F (°C)
J17 from the ACU. Plug in dryer or reconnect
32° (0°)
power and repeat step 5. Perform voltage
86° (30°)
check inside header J17 on ACU, between pins
104° (40°)
2 & 4—DO NOT SHORT PINS TOGETHER.
122° (50°)
140° (60°)
158° (70°)
HE – Heater (Condenser dryer)/
203° (95°)
Compressor (HP dryer)
Condenser dryer HP dryer
4. Check J6-1 and J6-3 to dryer cabinet ground. If either
J5-1 L2 J5-1
pin indicates continuity to ground (short), replace wiring
J5-2 Heater 1 J5-2
harness; otherwise, proceed to step 5.
J5-3 Heater 2
5. If the preceding steps did not correct the problem, replace
the ACU.
WI1 – MCU Communication
J12-2 +12VDC
J12-3 IN/OUT
J12-4 GND
SET1 SET2
HE – Heater/
Compressor
59°F (15°C) = 18.47 k ohms
T
3 1
BR BR
IF – RFI
THERMISTOR (NTC)
Whirlpool Compact Heat Pump Dryer
COMPONENT TESTING
(Heat Pump Dryer)
RESISTANCE
k ohms
35.975
9.786
6.653
4.608
3.243
2.332
HX-SLE – Heat
1.093
Exchanger Switch
and Level Switch
L2
J8-1 Heat Ex 1
Compressor
J8-2 Heat Ex 2
J8-3 Float 1
J8-4 Float 2
SET1 – NTC Air Channel
J7-1 NTC Air 1
J7-3 NTC Air 2
SET2 – NTC Heater
SEH
J6-1 NTC Heat 1
J6-3 NTC Heat 2
Figure 2 - Thermistor
BU
J6-3
DO NOT REMOVE OR DESTROY
RESISTANCE
Tolerance (%)
± 5.8
± 3.7
± 3.1
± 2.6
± 2.0
± 2.5
± 3.7
Thermistor NTC
ACU
n
3-11