Component Testing; Test #1: Ccu Power Check - Whirlpool WED99HEDW0 Technical Education

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 DRYER 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.
• 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 will damage the connectors.
n
6-4 HybridCare™ Dryer with Heat Pump Technology
For Service Technician Use Only

TEST #1: CCU 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: 240VAC
(electric 2-phase) or 208VAC (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 to access the machine electronics.
4. CCU VAC – With voltmeter set to AC, connect black probe
to CCU P8-3 (N) and red probe to P9-2 (L1). (See Figure 1.)
Plug in dryer or reconnect power.
¾ If 120VAC is present, unplug dryer or disconnect power
and go to step 5.
¾ If 120VAC is not present, unplug dryer or disconnect
power and perform TEST #2: Supply Connections, page 11.
5. CCU +5VDC – With voltmeter set to DC, unplug connector
P2 from the CCU and connect black probe to CCU P2-3
(ground) and red probe to P2-1 (+5V DC). Plug in dryer or
reconnect power.
¾ If +5VDC is present, unplug dryer or disconnect power
and go to step 8.
¾ If +5VDC is not present, go to step 6.
6. Unplug dryer or disconnect power. Unplug P14 from the
CCU. Plug in dryer or reconnect power and repeat step 5.
¾ If +5VDC returns, one of the thermistors has shorted.
To diagnose thermistors, see TEST #4a, page 16.
¾ If +5VDC is not present, go to step 7.
7. Unplug dryer or disconnect power. Reconnect P14 to
the CCU and unplug P2 from the CCU. Plug in dryer or
reconnect power and repeat step 5. Perform voltage
check inside header P2 on CCU, between pins 1 & 3—DO
NOT SHORT PINS TOGETHER.
¾ If +5VDC is still missing, unplug dryer or disconnect
power and replace the CCU.
¾ If +5VDC returns, unplug dryer or disconnect power and
check harnesses and connections between the CCU and
user interface (UI). If acceptable, replace the UI.
8. CCU +12VDC – with voltmeter set to DC, connect black
probe to CCU P5-3 (ground) and red probe to P5-8
(+12VDC). Plug in dryer or reconnect power.
¾ If +12VDC is present, go to step 9.
¾ If +12VDC is not present, unplug dryer or disconnect
power and replace the CCU.
9. Unplug dryer or disconnect power.
10. Reassemble all parts and panels.
11. Perform steps under "Install Diagnostics", page 5-4, to
verify repair.
Continue to next page for CCU board diagram
and CCU connectors & pinouts