Haier WQP12-B9227E Operating manual

Contents
Technical Service Manual
Dishwasher
Specification 2
Test program 24
Theory of parts 5-23
Function Description 3-4
Inspection 29-33
Location 5
PCB 6-7
Inlet valve 8-10
Drain pump 11-12
Heater 13-14
Washing pump 15-16
Procedure 25
Error code 26-28
Water circuit 3-4
Pressure switch 17
NTC 18-19
Flowmeter 20-21
Safety Hose 22-23
Troubleshooting 34-38
SAFETY NOTICE
This documentation is only intended for qualified technicians
who are aware of the respective safety regulations.
- 1 -

Specifications
For the basic operation instructions, please refer to the
instruction manual attached with each unit.
Electrical supply 220-240V, 50Hz
Supply water pressure 0.04MPa-1.0MPa
Supply water temperature below 60℃
-2 -
Models:WQP12-B9227E

washing pump
pressure switch
drain pumb
drain hose
over flow switch
air breaker
inlet valve
inlet hose
Regeneration water route
upper spray arm
top spray
tube
Inlet water route
lower spray arm
softener
Water circuit scheme
regeneration valve
Cycle water route
Drain water route
Water Circuit Function Description->
- 3 -

Process of water inlet (indicated by magenta route)
In this process, regeneration water route is cut off, main water route is open. The water in the main water
route is softened when pass through the softener, and then enter in the tub. During this phase, some of inlet
water will be stored in the air breaker to be regenerating water.
Process of cycle washing (indicated by blue route)
Cycle washing action is driven by washing pump motor. Water can obtain the power during it passing through
the working washing pump, then be pumped into spray arm, pass from spray arm nozzles, over the dishes,
into sump ,where connect to washing pump, and to get in the next water cycle.
Process of regeneration (indicated by green route)
Regeneration valve is open, the regenerating water dissolve salt in the salt chamber of softener, and then
enter in the resin tank to reactivate the resin.
Water Circuit Function Description->
- 4 -

Location Theory of parts->
Inlet valve
Washing pump
Capacity Softener Overflow switch
Filter system
Heater
Over Heat Proof
Micro-switch
Dispenser
Sump
Water inlet
Air breaker
Pressure switch(83/63)
(only for models whose water filling
be controlled by pressure switch)
Pressure switch(140/120)
Please Note: Exploded view and part list of each model have some different visions, so
please refer to newest vision Midea sent you.
- 5 -

PCB Theory of parts->
Printed Circuit Board is the control center of dishwasher, which receive and process signal
from components, send order to components and deal with the feedback information, etc.
Removing the control panel
The control panel can be removed from dishwasher door.
1. Remove the six screws securing the control panel to the door.
2. The control panel will drop down and be free of the door. But, the wiring will
still connected to the control panel.
S
08
1
2
on
Off
Access PCB
3. Disconnect the connector form PCB.
4. Remove the screws securing the PCB to control panel.
5. Remove the PCB.
6. Reverse the above procedure to install.
PCB
Note: For the majority of models, the PCB is located behind the control panel. The minority
of models locate the PCB on the side of strengthening muscle. You can judge the location by
the newest exploded view Midea sent you.
- 6 -

PCB Theory of parts->
Map of PCB
Description
Mark Function
HEAT Output for Heating Element
ACL Input of live wire
ACN Input of bull line
IS Input of Door Switch
EV1-L Firewire input of inlet valve
RE Thermister
ML Washing Pump
PS Drain Pump
D/ED Dispenser
EV1 Inlet valve
EV2 Softener
EV3 Halfload Valve
ISS Salt detect
ISB Rinse detect
IAQS Overflow detect
FM Flowmeter
FAN Fan
Note: This map is applies to 9378A model.
There is small pole’s location difference
between different models.
But the marks on PCB have the same
meaning .described on the left side
- 7 -

Technical data
Location of inlet valve Appearance
Inlet Valve Theory of parts->
The work principle
The inlet valve is electromagnetic valve that decide whether water enter or not. Valves are
normally closed. Each time the appliance requires water, the controller will convey an
electric signal to the coils to open the valves.
The inlet valve consist of electric coil, valve body, valve pole, filter etc.
In a word, the electromagnetic valve can act to allow water enter into machine, when it
receive the order given by controller.
to air breaker
connect to
inlet water hose
terminals
electric coil inside
The defeat point
1. The valve coil is broken, so the valve can’t open. It will cause the E1 error.
2. The filter is jammed, so water can’t enter. It will cause the E1 error.
3. The connector is loose, so the valve can’t open. It will cause the E1 error.
4. The valve pole is rusted or locked by dreg, so the valve can’t open or close. It will cause
the E1 or E4 error.
Nominal voltage 220-240VAC
Frequency 50/60Hz
Resistance Approx:3.4－4.3kΩ
100%ED T25
3min/5min T60
Flux 4L/min ±15％
Power 6W
Work Pressure 0.04－1MPa
Work duty
- 8 -

Inlet Valve Theory of parts->
3. Top panel
4. Left side panel
1. Baseboard
2. Left baseboard
5. Middle rear
crosspiece
Inlet valve
Access inlet valve
1. Disconnect power.
2. Remove the water inlet hose. (Note : Be careful of remain water drop.)
3. Remove the baseboard, left baseboard, top panel, left side panel and middle rear
crosspiece.
4. Disconnect the 2 terminal lugs
from the inlet valve.
5. Push the valve from the lower
rear crosspiece to take it off.
6. Remove the clamp and
disconnect the inlet hose (to air
breaker) from the water valve.
7. Reverse the above procedure
to install.
1.Open the control panel and take out the PCB;
2.Unplug the CON3 and P4 wires , then use the multi-
meter Ω shelf to measure resistance between the blue
wire (EV1) and white wire (IS), the normal resistance is
about 3.4KΩ to 4.3KΩ.
3. I f the measured resistance is not correct, it means the
valve coil is broken or the connector is loose. In this
case, we should check the connection first. If the
problem hasn’t been solved by re-connection, we should
replace the valve..
4.If the resistance is OK, we need to inspect the valve
body.
Inspect inlet valve
unplug
Check electric part
Attention: Build in models have no Baseboard and
left and right baseboard, but adjustable baseboard.
- 9 -
IS
EV1

Inlet Valve Theory of parts->
Check machine part
1. If the electric part is OK, we need to check the machine part.
2. Remove the baseboard, left baseboard, top panel, left side panel and middle rear
crosspiece.
3. Check the valve filter. if the valve filter is blocked, we need clear the residues.
4. If the valve filter is clear and the valve can’t inlet water, check whether valve can act or
not. If it isn’t , we need replace the valve.
5. If the water is continue entering, we need replace the valve.
- 10 -

Drain Pump Theory of parts->
Bottom View
Location of Drain Pump
Technical data
The work principle
to washing pump
connect to drain hose
motor
terminals
Drain pump integrated into sump
The work principle
Drain pump consists of electrical motor, impeller, inlet and outlet.
Drain pump is a kind of pump driven by permanent magnet synchronous motor. The rotor is
made with permanent magnet material, the running inertia of rotor is very small, the stator
consist of silicon steel stack and coil. When the drain pump is on power, the rotor will be
very easy to start.
The defeat point
1. The motor coil is broken, so the drain pump can’t work. It will cause the E2 , E4 or E1 error
.
2. The magnetism of motor rotor is weak, so drain pump cannot work. It will cause the E2, E4
or E1 error .
3. The connector is loose, so the drain pump can’t work. It will cause the E2, E4 or E1 error .
4. The rotor is locked by residues, so the drain can’t work . It will cause the E2, E4 or E1
error .
5.The drain pump assembly rack is loose, it will cause noise.
6.The non-return valve is bad, the remain water is too much.
Explanatory notes: failure of drain pump may cause E1, becaus
Nominal voltage 220-240VAC
Frequency 50Hz
Resistance 150－220Ω
Delivery height 1M
Delivery performance ≥17l/min(230VAC)
- 11 -

Drain Pump Theory of parts->
Check the machine part
1. If the electric part is OK, we need to check the machine part.
2. Remove bottom board.
3. If the non-return valve is wrongly assembled, the tub will remain much water. We need to
re-assemble the non-return valve.
4. If the drain pump is working, but no water drain out or just a little. We should check the
drain hose or drain body.
1. Drain off the water in the dishwasher, and
disconnect the power supply。
(Note : Make sure to remove remained water in the
dishwasher. If not, wet the floor.)
2. Remove four screws on bottom, and then
remove bottom board.
3. Label and disconnect the two terminal lugs from
the drain pump.
4. Remove screws securing the drain pump to
sump, then remove drain pump.
5. Reverse the above procedure to install.
Access drain pump
Inspect drain pump
Check the electric part
1.Open the control panel and take out the PCB;
2.Unplug the CON4 and P4 wires, then use the multi-
meter Ω shelf to measure the red wire (PS) and white wire
(IS), the normal resistance is about 150Ω to 220Ω.
3. If the measured resistance is not correct, it means the
pump coil is broken or connector is loose. In this case, we
should check the connection first. If the problem hasn’t
been solved by re-connection, we should replace the
drain pump.
4.If the resistance is OK, but it also can’t work, maybe the
magnetism is too weak, so we need to replace the drain
pump.
- 12 -
IS
PS

The defeat point
1. The heater coil is broken, so the heater cannot work. It will cause the E3 error.
2. The thermostat is active, so the heater cannot work. It will cause the E3 error.
3. The connector is loose, so the heater cannot work. It will cause the E3 error.
Heater Theory of parts->
Bottom View
The work principle
Technical data
Location of Heater
pressure switch
Nominal voltage 230VAC
Rating power 1800W
Resistance 29.265±1.463Ω
Thermastat1 98℃
Thermastat2 229 ℃
- 13 -

Inspect heater
1. Remove bottom board.
2. Use the multi-meter Ω shelf to measure resistance
between the two terminals shown in right picture, the
resistance is about 29Ω to 31Ω.
3. If the measured resistance is not correct, it means the
heater coil or the thermostat is broken, we should replace
the heating element or the thermostat.
Heater Theory of parts->
Bottom View
Access heater
1. Drain off the water in the dishwasher, and disconnect the power supply.
(Note : Make sure to remove remained water in the dishwasher. If not, wet the floor)
2. Remove bottom board.
3. Label and disconnect the terminals to and ground wire.
4. Remove the 2 clamps from the Heating element.
Caution: The clamp is easily damaged during removal and can’t be reused. Replace the old
clamp with a new universal clamp .
5. Reverse the above procedure to install.
Clamps
Ground terminal
Terminals
(measure heater resistance)
terminals
- 14 -

BLUE
BLACK
M
BLUE
A150℃
RED
Washing Pump Theory of parts->
Bottom View
Location of Washing Pump
Technical data
The work principle
Washing pump is a kind of asynchronism
motor with capacitor. The stator consist of
silicon steel stack and two coils, main coil and
assistant coil .
The defeat point
1. The motor coil is broken, so the wash pump can’t work. It will cause E3 error.
2. The motor rotor capacitor is weaken, so washing pump can’t start. In this case, it will
send out the electromagnetism noise. If it is continue electrifying motor, the thermal
protector will work. It will cause E3 error.
3. The connector is loose, the wash pump can’t work. It will cause E3 error.
4. The rotor is locked by residues, so the wash pump can’t work . It will cause the E3 error.
5.The drain pump assembly bracket is loose, it will cause noise.
6.If the machine hasn’t been used for long time, there is a possibility the wash pump can’t
starting.
M-main coil
A-assistant coil
Models
Items YXW65-2B YXW50-2
Nominal voltage 220-240VAC 220-240VAC
Frequency 50Hz 50Hz
Main coil: 84.8±7%Ω Main coil:93.10±7%Ω
Assistant coil:78.6±7%Ω Assistant:95.99±7%Ω
Delivery height 0.8m 1m(230VAC)
Delivery
performance ≥50l/min(230VAC) ≥50l/min(230VAC)
Lock rotor
current ≤1.50A 1.0±10%(230VAC)
Operating
current 0.65A±10% 0.47±10%(230VAC)
Capacitor 5μF 3μF
Resistance
- 15 -

Washing Pump Theory of parts->
Check the machine part
1. If the electric part is OK, we need to check the machine part.
2. Remove bottom board.
3. Check the pump assembly, if the bracket is loose, it will bring the noise, we need to
tighten it.
4. If the wash pump cannot start and the machine hasn’t been used too long, maybe the
seal element is bond.
5. If the drain pump is working, but no water out or just a little. We should check the vane
wheel.
Access Washing Pump
1. Disconnect power.
2. Remove bottom board.
3. Label and disconnect the 2 terminals to the capacitor.
4. Label and disconnect the 2 terminals to the motor wire connector.
5. Remove the clamp fastening the interconnect hose to the sump.
Caution: The clamp is easily damaged during removal and can’t be reused. Replace the old
clamp with a new universal clamp (Dia-31.0mm)
6. Remove the clamp fastening interconnect hose to the lower nozzle .
7. Remove the clamp fastening interconnect hose to heater.
8. Remove the screw and disconnect the ground wire from the wash pump motor assembly.
Note: Do not attempt to remove the bolt and locknut connecting the motor mount to the
dishwasher frame.
9. Remove the motor pump assembly from the dishwasher.
10. Reverse the above procedure to install.
Inspect Washing Pump
Check the electric part
1.Open the control panel and take out PCB;
2.Unplug the CON4 and P4 wires, then use the multi-
meter Ω shelf to test resistance between two white wire
(ML and IS), the normal resistance is about 78Ω to 100
Ω.
3. I f the resistance is not correct, it means the pump coil
is broken or the connector is loose, In this case, we
should check the connection first. If the problem hasn’t
been solved by re-connection, we would replace the
washing pump.
4.If the resistance is OK but it cannot work, it maybe the
capacitor weakly, we need to replace the capacitor.
- 16 -
IS
ML

The pressure switch consists of a moving diaphragm and disc which activate a
change over contact. The contact can be calibrated to trip and reset at the
desired pressure levels, The main application is to control the level of water in
appliances. May also provide flood protection.
In our production, the pressure switch is to control the water level in appliance,
like 83/63 serial. May also provide flood protection, like 140/120 serial.
Manufacturer : EMZ
11 - COM
12 - NC
14 - NO
Front view Back view
11
14
12
23
1
Back view
Front view
Manufacturer:Elbi
1- COM
2 - NC
3 - NO
Pressure Switch Theory of parts->
The work principle
- 17 -

NTC Theory of parts->
NTC
Bottom View
Location of NTC The work principle
The work principle
Negative Temperature Coefficient Thermistor is integrated into sump, which is used for
measuring temperature of water in the tub.
Access Washing Pump
1. Remove bottom board.
2. Remove two screws securing the NTC to sump(shown in above picture).
3. Take out NTC.
4. Reverse the above procedure to install.
screws
- 18 -

NTC Theory of parts->
15℃ 17.48KΩ
20℃ 12.12KΩ
25℃ 10KΩ
30℃ 8.299KΩ
40℃ 5.807KΩ
50℃ 4.144KΩ
60℃ 3.011KΩ
70℃ 2.224KΩ
80℃ 1.667KΩ
85℃ 1.451KΩ
NTC
Inspect NTC
1.Open the control panel and take out PCB;
2.Unplug the RE connector(shown in below picture), then use the multi-meter Ω shelf to test
resistance between two blue wire , the normal resistance is shown in below table.
3. I f the resistance is not correct, it means NTC circuit has a problem. In this case, we
should check the connection first. If the problem hasn’t been solved by re-connection, we
would replace the NTC.
unplug
NTC resistance table
- 19 -

Flowmeter Theory of parts->
Location of Flowmeter
The work principle
Flowmeter
Flowmeter is integrated into Air Breaker. Function of
Flowmwter is measure how much water has entered in
appliance. it consists of impeller, tongue tube and
terminal, etc.
When water pass through the flowmeter, moving water
can rotate magnetic impeller, the tongue tube can sense
the impeller’s magnetic and send electronic pulses.
Top Panel
Side panel
Left Baseboard
Baseboard
Attention: Build in models have no Baseboard and left and
right baseboard, but adjustable baseboard.
- 20 -