Test #1: Acu Power Check - Whirlpool 4.3 CU FT Service Manual

COMPONENT TESTING
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.
Component Testing
TESTING WASHER COMPONENTS FROM THE
CONTROL
Before testing any of the components, perform the following
checks:
• The most common cause for mis-diagnosed control
failure is poor connections. Therefore, disconnecting,
inspecting and reconnecting wires will be necessary
throughout test procedures.
• All tests/checks should be made with a VOM or DVM
having a sensitivity of 20,000 ohms-per-volt DC, or
greater.
• Check all connections before replacing components,
looking for broken or loose wires, failed terminals, or
wires not pressed into connectors far enough.
• IMPORTANT: Voltage checks must be made with all
connectors attached to the boards.
• Resistance checks must be made with power cord
unplugged or power disconnected, and with wiring
harness or connectors disconnected from the control.
The testing procedures in this section may require the use
of needle probes to measure voltage. Failure to use needle
probes may damage the connectors.
n
3-4 Whirlpool Compact Heat Pump Dryer
For Service Technician Use Only

TEST #1: ACU Power Check

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 outlet: 240 VAC
(electric 2-phase) or 208 VAC (electric 3-phase).
¾ If line voltage is present, go to step 3.
¾ If line voltage is not present, check for tripped circuit
breaker or blown household fuse. If CB (circuit breaker)
is not tripped, have customer check with qualified
electrician.
3. Remove top panel, left side panel, and console to access
the machine electronics.
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.) Plug in dryer or reconnect power.
¾ If 240 VAC is present, unplug dryer or disconnect
power and go to step 5.
¾ If 240 VAC is not present, unplug dryer or disconnect
power and perform TEST #2: Supply Connections, page
13.
5. ACU +5 VDC – With voltmeter set to DC, unplug connector
J17 from the ACU and connect black probe to ACU J17-4
(ground) and red probe to J17-2 (+5 VDC). Plug in dryer or
reconnect power.
¾ If +5 VDC is present, unplug dryer or disconnect power
and go to step 8.
¾ If +5 VDC is not present, go to step 6.
6. Unplug dryer or disconnect power. Unplug J7 and J6 from
the ACU. Plug in dryer or reconnect power and repeat
step 5.
¾ If +5 VDC returns, one of the thermistors has shorted.
To diagnose thermistors, see TEST #4c, page 17.
¾ If +5 VDC is not present, go to step 7.
7. Unplug dryer or disconnect power. Reconnect J7 and J6
to the ACU and unplug J17 from the ACU. Plug in dryer
or reconnect power and repeat step 5. Perform voltage
check inside header J17 on ACU, between pins 2 & 4—DO
NOT SHORT PINS TOGETHER.
¾ If +5 VDC is still missing, unplug dryer or disconnect
power and replace the ACU.
¾ If +5 VDC returns, unplug dryer or disconnect power
and check harnesses and connections between the
ACU and user interface (UI). If acceptable, replace the
UI.
8. ACU +12 VDC – with voltmeter set to DC, connect black
probe to ACU J12-4 (ground) and red probe to J12-2 (+12
VDC). Plug in dryer or reconnect power.
¾ If +12 VDC is present, go to step 9.
¾ If +12 VDC is not present, unplug dryer or disconnect
power and replace the ACU.
9. Unplug dryer or disconnect power.
10. Reassemble all parts and panels.
11. Perform the Service Test Cycle on pages 3 and 4 to verify
repair.