Panasonic Cu 3ke19nbucu Technical Service Manual

							8-2.  Trouble Diagnosis by Error Monitor Lamps
8-2-1.  Location of the Error Monitor Lamps
Remove the top plate of outdoor unit and the cover of Electrical Component Box.
The Power Lamp and Error Monitor Lamps are located on the P.C.Board of Electrical Component Box. (Fig.1)
8-2-2.  Display of the Error Monitor Lamps
If a protective device has activated or there is a sensor failure in the outdoor unit, the 4 error monitor lamps on the 
outdoor control circuit board will indicate the nature of the trouble.
Heat Exchanger Rear side P.C.Board of Electrical Component Box.
Error Monitor Lamps
Front side
Fig.1 View from top
ERR0
ERR1
ERR2
ERR3Power Lamp
Error Monitor Lamp
Error Contents
ERR0 ERR1 ERR2 ERR3
Sensor for compressor discharge temp
Sensor for heat excharge temp
Sensor for branch pipe A (Narrow tube)
Sensor for branch pipe B (Narrow tube)
Sensor for branch pipe C (Narrow tube)
Sensor for branch pipe D (Narrow tube)
Sensor for branch pipe A (Wide tube)
Sensor for branch pipe B (Wide tube)
Sensor for branch pipe C (Wide tube)
Sensor for branch pipe D (Wide tube)
HIC circuit trouble (current, temp)
Actuation of comp over load relay
Actuation of freeze protection function
Outdoor unit error. Detail of error message indicate on indoor LED Outdoor temp sensor
: ON : OFF
To prevent electric shock, do not inspect or repair until the Power Lamp on 
the P.C.Board is turned off.Warning
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							8-3-1.  Checking the outdoor unit
8-3.  Checking the Outdoor System
8-3-2.  Checking the defrost operation
Work procedure
Apply 220 V AC between terminals L1 and L2 on the 
outdoor unit terminal plate. •
Short-circuit the T-RUN terminal to the COM terminal 
of TEST/T-RUN terminals. •The LED (red) on the control board must illuminate. •
The compressor, fan motor, 4-way valve, and solenoid 
valve (for the hot gas bypass) must turn ON.
(They turn ON about (70) seconds later after the power 
is turned ON.) •
No.
1
2Check items (unit operation)
Work procedure
Connect a dummy resistor of 39 k ohm to the outdoor
coil temperature sensor connector. •Non-stop defrost
The maximum length of defrost operation is 12 
minutes.
Defrost can also be released based on the below
conditions for the outdoor heat exchanger sensor.
*1  However, the condition is (68 °F) or higher when
      the outdoor air temperature is below 32 °F.Less than 2 minutes     Not released
2 minutes or more     57.2 °F or higher (*1) •
No.
1Check items (unit operation)
Indoor fan
Outdoor fanCM
Solenoid valve
(for hot gas
bypass)30 sec.
10 sec. 5 sec.(80 Hz)
ON
ON OFF OFF
OFF ON
Defrost start ReleaseON Setting Setting
LLStop
NOTEIf the above check items are okay, but the outdoor unit does not operate, there may be a faulty 
connection between the indoor unit and the outdoor unit.
Using forced defrost operation to check this  function.
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							8-4.  Trouble Diagnosis of Each Part
8-4-1.  Problems of Each Part and Inspection Points
For details about the inspection points, refer to the Inspection Points for Each Part.
Problems
Inspection
pointsIndoor unit
Indoor unit does not operate.
Self-Diagnostics check
Indoor controller 
(control unit)
Indoor fan motor
Room temperature 
sensor
Heat exchanger 
temperature sensor
Inter-unit cable
Switch circuit board
Outdoor control circuit 
board
Diode module
HIC
Electrolytic capacitor
Fuse
Compressor
Compressor protective 
sensor
Outdoor fan motor
4-way valve
Coil thermistor
Electric expansion valve
Branch tubing 
temperature sensor
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Operation lamp blinking.
Operation lamp does not illuminate.
Indoor fan dose not turn.
Outdoor unit does not operate.
Outdoor fan dose not turn.
4-way valve does not operate.
The compressor (only) does not 
operate.
The compressor stops on occasion.
The compressor speed does not
increase.
The outdoor air temperature is high,
however defrost operation occurs.
Defrost operation does not occur.
The electric expansion valve does
not operate.
Does not cool or cooling
performance is inadequate.
Does not heat or heating
performance is inadequate.
Outdoor unit Others
No. of 
Inspection
Points for
Each part
Indoor unit Outdoor unit
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							Problems
Inspection
pointsIndoor unit
Indoor unit does not operate.
Breaker
Refrigerant gas pressure(9)
(10)
Operation lamp blinking.
Operation lamp does not illuminate.
Indoor fan dose not turn.
Outdoor unit does not operate.
Outdoor fan dose not turn.
4-way valve does not operate.
The compressor (only) does not
operate.
The compressor stops on occasion.
The compressor speed does not
increase.
The outdoor air temperature is high,
however defrost operation occurs.
Defrost operation does not occur.
The electric expansion valve does
not operate.
Does not cool or cooling
performance is inadequate.
Does not heat or heating
performance is inadequate.
Outdoor unit Others
No. of 
Inspection
Points for
Each part
Others
8-4-2.  Inspection Points for Each Part
(1) Outdoor control circuit board
Refer to "8-3-1. Checking the outdoor unit".
(2) Fuse
Check it visually or the continuity with a tester.
(3) Compressor
Check for an open circuit in the compressor coil winding.
(4) Compressor protective sensor (compressor discharge temperature thermistor)
Check that the senseor is securely contained in the thermostart holder.
(5) 4-way valve
Short-circuit the T-RUN terminal to the COM terminal of TEST/T-RUN terminals. Perfrom a test run of the unit 
alone, and check whether the 4-way valve inside the outdoor unit produces a click sound.
(6) Coil thermistor
Check that the sensor is securely contained in the thermostat holder.Do not remove or insert the outdoor control circuit board connector when power is being supplied to it.
(The controller will be damaged.)
NOTE
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							No voltage on circuit board
(7) Electric expansion valve
When replacing the electric expansion valve and coil, be sure to attach the connectors in the correct positions. 
Labels are applied to the valve body and coil, corresponding to the connector colors, to identify them.
Controller check
Voltage varies
0 ohm
No temperature change Temperature changes Replace the coil.
Open and close the 
electric expansion valve 
by hand to check it.
Replace the electric 
expansion valve.This part is normal.
Check elsewhere. Check the illumination 
of the red Power Lamp.
Replace the controller.Check the coil resistance.Use a multi-meter to measure the voltage (12 V).
Model No. Sequence
CU-3KE19NBU
CU-4KE24NBU
CU-4KE31NBUMV0 MV1 When the power is turned ON, the needle will move in the 
following seguence in approximately 10 to 20 seconds for 
each point.
Check the resistance between the gray lead 
wire and the other wires.
Resistance is OK if it is 46 + / – 4ohm at 68 °F
Cool the main unit with 
a damp cloth or other 
means while welding.
When applying 
vacuum, use the 
special service magnet 
and rotate at least 5 
revolutions 
counterclockwise to 
fully open the electric 
expansion valve.
Use the special service magnet and 
rotate 5 revolutions clockwise to fully 
close the valve.
Then start the unit and measure the 
temperature at the inlet and outlet 
tubes of the electric expansion valve.
If the temperature difference is large, 
the valve is closed.
Then rotate 5 revolutions 
counterclockwise to open the valve. 
Operation is normal if the temperature 
difference between the 2 tubes drops.*1
Approx. 46 +/– 4 ohm
NOTE
*1 If you have manually checked the electric expansion valve, be sure to reapply the outdoor power after you have
     replaced the wiring. (The position of the elecric expansion valve will changed.)
MV2
MV0 MV1MV2MV3
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							(8) Branch tubing temperature sensor
Check that the sensor is securely contained in the thermostat holder.
(9) Breaker
Check whether or not the breaker has been tripped.
Check that the breakers and fuses used are of the specified capacity.
Check that the breaker and its line are exclusive for A/C use.
(10) Refrigerant gas pressure
Start a COOL test run, and messure the temperatures of the A/C intake air and discharge air. Compare the values 
with the performance charts.
If the values are higher than the performance charts:
Check for refrigerant shortage or blockage of the refrigerant circuit.
    < Assessment of refrigerant shortage >
        1. The pressure in the low-pressure section is 5 MPa or more below the value in the performance charts.
        2. There is little condensation on the indoor heart exchanger, which overall appears dry.
    < Distinguishing between refrigerant shortage and refrigerant circuit blockage >
       If the pressure in the low-pressure section does not change when the circuit is charged 2 to 3 times with
       refrigerant gas (0.44 lbs each time), or if the change is small, then the problem may not be 
       refrigerant shortage. 
      The problem may be a blockage of the refrigerant circuit.
        1. Check that there is no internal leakage inside the 4-way valve:
        At the low-pressure side tubing, check that there is no temperature difference between the intake and
        discharge of the 4-way valve.
        2. Check that the electric expansion valve is not blocked. Check as described on the preceding page.
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							8-5.  Trouble Diagnosis of Fan Motor
This outdoor DC fan motor contains an internal control PCB. Therefore, it is not possible to measure the coil 
resistance, and the following procedure should be used to check the motor.
Perform the trouble diagnosis by Test Run mode described on Installation Instructions of indoor unit.
[Trouble symptom 1] The fan does not stop when the outdoor unit stops.    Outdoor unit controller trouble
[Trouble symptom 2]  The fan motor does not rotate when the outdoor unit is operating.
(Diagnostic procedure)
* Disconnect the motor connectors and measure the voltage at the DC motor connectors on the outdoor 
unit controller (3 locations).
(Diagnostic results)
All of the above measured values are normal.     Fan motor trouble (Replace the motor.)
Any one of the above measured values is not normal.     Outdoor unit controller trouble 
(Replace the controller .)
(Reference) DC motor connector pin arrangement
[Trouble symptom 3] Motor rotates for some time (several seconds), but then quickly stops, when the outdoor 
unit operates.
(There is trouble in the system that provides feedback of motor rotation speed from the 
motor to the outdoor unit controller.)
[Trouble symptom 4] Fan motor rotation speed does not change during outdoor unit operation.
[Trouble symptom 5] Fan motor rotation speed varies excessively during outdoor unit operation.
(Remedy for symptom 3 to 5)
It is not possible to identify whether the trouble is outdoor unit controller trouble or motor trouble. 
Therefore, first replace the outdoor unit controller, then (if necessary) replace the DC motor.
Important:(A) Turn OFF the power before connecting or disconnecting the motor connectors.
(B) When performing voltage measurement at the outdoor controller connector for (3) in the table 
below, the DC motor will trip and voltage output will stop approximately 10 seconds after 
operation is started. For this reason, to measure the voltage again, first turn OFF the outdoor 
unit power, then, measure the voltage in Test Run mode.
(1) Vm-Gnd: Between pin 1 and pin 4
(2) Vcc-Gnd: Between pin 5 and pin 4
(3) Vsp-Gnd: Between pin 7 and pin 4Measurement location
DC 230V or more
DC 14V or more
After fluctuating 4 times between DC 1.7 to 6.1V
(1 sec. ON) and DC 0 V (1 sec. OFF), the DC
motor trips.Normal value
Pin 1: Vm (red)
Pin 2: Not used
Pin 3: Not used
Pin 4: Gnd (blue)
Pin 5: Vcc (brown)
Pin 6: PG (white)
Pin 7: Vsp (orange)
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							9.  REFRIGERANT R410A: 
SPECIAL PRECAUTIONS WHEN SERVICING UNIT
9-1.  Characteristics of New Refrigerant R410A
9-1-1.  What is New Refrigerant R410A?
R410A is a new refrigerant that contains two types of pseudo-non-azeotropic refrigerant mixture. Its 
refrigeration capacity and energy efficiency are about the same level as the conventional refrigerant, R22.
9-1-2.  Components (mixing proportions)
HFC32 (50%) / HFC125 (50%)
9-1-3.  Characteristics
Less toxic, more chemically stable refrigerant
The composition of refrigerant R410A changes whether it is in a gaseous phase or liquid phase. Thus, when 
there is a refrigerant leak the basic performance of the air conditioner may be degraded because of a change in 
composition of the remaining refrigerant. Therefore, do not add new refrigerant. Instead, recover the 
remaining refrigerant with the refrigerant recovery unit. Then, after evacuation, totally recharge the specified 
amount of refrigerant with the new refrigerant at its normal mixed composition state (in liquid phase).
When refrigerant R410A is used, the composition will differ depending on whether it is in gaseous or liquid 
phase, and the basic performance of the air conditioner will be degraded if it is charged while the refrigerant is in 
gaseous state. Thus, always charge the refrigerant while it is in liquid phase. 
Ether-type oil is used for compressor oil for R410A-type units, which is different 
from the mineral oil used for R22. Thus more attention to moisture prevention and 
faster replacement work compared with conventional models are required. 
CAUTION
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							Tubing precautions
Refrigerant R410A is more easily affected by dust or moisture compared with R22, thus be sure to temporarily 
cover the ends of the tubing with caps or tape prior to installation.
Never use 0.0276" (0.7 mm)-thick copper tubing or tubing which is less than 0.0315" (0.8 mm) in thickness, since 
air conditioners with R410A are subject to higher pressure than those using R22 and R407C.
No addition of compressor oil for R410A
No additional charge of compressor oil is permitted.
No use of refrigerant other than R410A
Never use a refrigerant other than R410A.
If refrigerant R410A is exposed to fire
Through welding, etc., toxic gas may be released when R410A refrigerant is exposed to fire. Therefore, be sure 
to provide ample ventilation during installation work.
Caution in case of R410A leak
Check for possible leak points with the special leak detector for R410A. If a leak occurs inside the room, 
immediately provide thorough ventilation.
A D
Flare tool for R410AA D
Conventional flare tool (R22)
Spacer
9-2.  Checklist before Servicing
Use a clutch-type flare tool for R410A or the conventional flare tool. Note that sizes of the resultant flares differ 
between these two tools. Where a conventional flare tool is used, make sure to observe A Specification (amount of 
extrusion) by using the flare spacer.
Size of flare
Specification A
Diameter of tube D
Dia.1/4" (6.35 mm)
Dia.3/8" (9.52 mm)
Dia.1/2" (12.7 mm)
Dia.5/8" (15.88 mm)Flare tool for R410A Conventional flare tool (for R22)
0 to 0.0196"
(0 to 0.5 mm)0.0472"
(1.2 mm)
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							9-3.  Tools Specifically for R410A 
For servicing, use the following tools for R410A
Gauge manifold
Charging hose
Gas leak detector
Refrigerant cylinder
Charging cylinder
Refrigerant recovery unit
Vacuum pump with anti-reverse flow (*1)
(Solenoid valve-installed type, which prevents oil from flowing back into the 
unit when the power is off, is recommended.)
Vacuum pump (*2)...can be used if the following adapter is attached.
Vacuum pump adapter (reverse-flow prevention adapter) (*3).
(Solenoid valve-installed adapter attached to a conventional vacuum pump.)
Electronic scale for charging refrigerant
Flare tool
Bender
Torque wrench 
Cutter, reamer
Welding tool, nitrogen gas cylinder
Tools specifically for R410ATool Distinction Tool Name
Tools which can be com-
monly used for R22,
R407C, and R410A
CAUTIONThe above tools specifically for R410A must not be used for R22 and R407C. 
Doing so will cause malfunction of the unit.
For the above vacuum pump (*1, *2) and vacuum pump adapter (*3), those for 
R22-type units can be used for R410A-type. However, they must be used 
exclusively for R410A and never alternately with R22 and R407C.
For details on tubing installation procedures, refer to the installation manuals attached to the indoor 
unit and outdoor unit. To prevent other refrigerants (R22, R407C) from being mistakenly charged to this unit, shape and external 
diameter of the service port screw has been altered.
     R410A : 5/16"
     R22, R407C : 1/4"
9-4.  Tubing Installation Procedures
When the tubes are connected, always apply HAB oil on the flare portions to improve the sealing of tubing.
The following is the HAB oil generally used:
Esso:  ZERICE S32
NOTE
90