Panasonic Cu 3ks19nbucu 4ksxxnbu Technical Service Manual

8.  TROUBLESHOOTING (BEFORE CALLING FOR SERVICE)
8-1.  Precautions before Performing Inspection or Repair
Both the indoor unit and outdoor unit include electronic control circuits. 
Be sure to pay attention to the following before inspecting or repairing the 
outdoor-side electronic circuits.
High-capacity electrolytic capacitors are used inside the outdoor unit controller (inverter). They retain an 
electrical charge (charging voltage DC 311 V) even after the power is turned OFF, and some time is...

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...

8-3-1.  Checking the outdoor unit
8-3.  Checking the Outdoor System
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 and fan motor must turn ON.
(They turn ON about (70) seconds later after the power 
is turned ON.) •
No.
1
2Check items (unit operation)
NOTEIf the above check items are okay, but the outdoor...

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...

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) Coil thermistor
Check that the sensor is securely contained in the thermostat holder.Do not remove or...

No voltage on circuit board
(6) 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...

(7) Branch tubing temperature sensor
Check that the sensor is securely contained in the thermostat holder.
(8) 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.
(9) 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...

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...

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...

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...