Panasonic Cs Kexxnb4x Cz 18bt1u Service Manual

							Fuse
PCB Ass'y
Fig. 5
Fig. 6
Fuse
10-2.  Checking Continuity of Fuse 
on PCB Ass'y
Remove the PCB Ass'y from the electrical 
component box. Then pull out the fuse from the PCB 
Ass'y. (Fig. 5)
Check for continuity using a multimeter as shown in 
Fig. 6.
61 
						

							11.  REFRIGERANT R410A: 
SPECIAL PRECAUTIONS WHEN SERVICING UNIT
11-1.  Characteristics of New Refrigerant R410A
11-1-1.  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.
11-1-2.  Components (mixing proportions)
HFC32 (50%) / HFC125 (50%)
11-1-3.  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
11-2.  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)
63 
						

							11-3.  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"
11-4.  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
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							11-5.  In Case of Compressor Malfunction 
CAUTIONShould the compressor malfunction, be sure to make the switch to a replacement 
compressor as quickly as possible.
Use only the tools indicated exclusively for R410A.     See "11-3. Tools Specifically 
for R410A."
11-5-1.  Procedure for Replacing Compressor
(1) Recovering refrigerant
Any remaining refrigerant inside the unit should not be 
released to the atmosphere, but recovered using the 
refrigerant recovery unit for R410A. 
Do not reuse the recovered refrigerant, since it will contain 
impurities. 
(2) Replacing Compressor
Soon after removing seals of both discharge and suction 
tubes of the new compressor, replace it quickly.
(3) Checking for sealing
Use nitrogen gas for the pressurized gas, and never use a 
refrigerant other than R410A. Also do not use oxygen or 
any flammable gas.
(4) Evacuation
Use a solenoid valve-installed vacuum pump so that 
even if power is cut off in the middle of evacuation of air 
due to a power interruption, the valve will prevent the 
pump oil from flowing back.
The equipment may be damaged if moisture remains in 
the tubing, thus carry out the evacuation thoroughly.
When using a vacuum pump with exhaust air volume more 
than 0.883 cu.ft./min. and ultimate vacuum pressure rate 
of 50 micron Hg.
Standard time for evacuation
(1) Recover refrigerant
OK
(2) Replace compressor
OK
(3) Check for sealing
OK
(4) Evacuation
OK
(5) Recharge
Length of tubing
Evacuation timeLess than 33 ft. (10 m)
More than 10 minutesMore than 33 ft. (10 m)
More than 15 minutes
65 
						

							Valve
Single valve
Charge liquid refrigerant with 
cylinder in up-side-down position.
Single valve (with siphon tube)
Charge with cylinder in normal position.Liquid
Valve
Liquid
Charging
cylinder
Open
Refrigerant
cylinder
Liquid
NO!
CAUTIONNever charge a large amount 
of liquid refrigerant at once to 
the unit. This may cause 
damage to the compressor.
CAUTIONTo prevent the composition 
of R410A from changing, 
never bleed the refrigerant 
gas into the atmosphere 
while transferring the 
refrigerant. (Fig. 3) (5) Recharging
Be sure to charge the specified amount of 
refrigerant in liquid state using the service port 
of the wide tube service valve. The proper 
amount is listed on the unit's nameplate. 
When the entire amount cannot be charged all at 
once, charge gradually while operating the unit in 
Cooling Operation.
When charging with a refrigerant cylinder, use an 
electronic scale for charging refrigerant. In this 
case, if the volume of refrigerant in the cylinder 
becomes less than 20% of the fully-charged 
amount, the composition of the refrigerant starts 
to change. Thus, do not use the refrigerant if 
the amount in the charging cylinder is less 
than 20%.
Also, charge the minimum necessary amount to 
the charging cylinder before using it to charge 
the air conditioning unit.
Example:
In case of charging refrigerant to a unit requiring 
1.68 lb. (0.76 Kg) using a capacity of a 22 lb. (10 
Kg) cylinder, the minimum necessary amount for 
the cylinder is: 
1.68 + 22    0.20 = 6.08 lb.
(0.76 + 10    0.20 = 2.76 Kg)
For the remaining refrigerant, refer to the 
instructions of the refrigerant manufacturer.
If using a charging cylinder, transfer the specified 
amount of liquid refrigerant from the refrigerant 
cylinder to the charging cylinder. 
Prepare an evacuated charging cylinder 
beforehand.
Do not use the refrigerant if the amount in the 
charging cylinder is less than 20%.
Configuration and characteristics of cylinders
Fig. 1
Fig. 2
Fig. 3
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							Length of tubing
Evacuation timeLess than 33 ft. (10 m)
More than 10 minutesMore than  33 ft. (10 m)
More than 15 minutes
11-6.  In Case Refrigerant is Leaking
CAUTIONNever attempt to charge additional refrigerant when refrigerant has been leaking 
from the unit. Follow the procedure described below to locate points of leaks and 
carry out repairs, then recharge the refrigerant.
(1) Detecting Leaks
Use the detector for R410A to locate refrigerant leak 
points. 
(2) Recovering refrigerant
Never release the gas to the atmosphere; recover residual 
refrigerant using the refrigerant recovery unit for R410A, 
instead.
Do not reuse the recovered refrigerant because its 
composition will have been altered.
(3) Welding leaking points
Confirm again that no residual refrigerant exists in the unit 
before starting welding.
Weld securely using flux and wax for R410A.
Prevent oxide film from forming inside the tubes utilizing 
substitution with nitrogen (N2) in the refrigerant circuit of 
the unit. Leave ends of tubes open during welding.
(4) Checking for sealing
Use nitrogen gas for the pressurized gas, and never use a 
refrigerant other than R410A. Also do not use oxygen or 
any flammable gas.
(5) Evacuation
Use a solenoid valve-installed vacuum pump so that 
even if power is cut off in the middle of evacuation of air 
due to a power interruption, the valve will prevent the 
pump oil from flowing back.
The equipment may be damaged if moisture remains in 
the tubing, thus carry out the evacuation thoroughly.
When using a vacuum pump with exhaust air volume 
more than 0.883 cu.ft./min. and ultimate vacuum pressure 
rate of 50 micron Hg.
Standard time for evacuation
(6) Recharging
Recharge unit in the same manner explained on the 
previous page "(5) Recharging."
(2) Recover refrigerant
OK
(3) Weld leaking points
OK
(4) Check for sealing
OK
(5) Evacuation
OK
(6) Recharge
(1) Detect leaks
OK
67 
						

							11-7.  Charging Additional Refrigerant
11-7-1.  When Tubes are Extended
Observe the proper amount of refrigerant as stated in this service manual or the installation manual that came 
with the indoor unit. Charge additional refrigerant in liquid state only. 
11-8.  Retro-Fitting Existing Systems
11-8-1.  Use of Existing Units
Never use new refrigerant R410A for existing units which use R22. This will cause the air conditioner to 
operate improperly and may result in a hazardous condition.
11-8-2.  Use of Existing Tubing
If replacing an older unit that used refrigerant R22 with a R410A unit, do not use its existing tubing. Instead, 
completely new tubing must be used.
CAUTIONNever charge additional refrigerant if refrigerant is leaking from the unit. Follow 
instructions given in "11-6. In Case Refrigerant is Leaking" and completely carry 
out repairs. Only then should you recharge the refrigerant.
68