Panasonic Cu 3ks19nbucu 4ksxxnbu Technical Service Manual

Outdoor Unit  : CU-4KS31NBU
Indoor Unit  : CS-MKS9NB4U × 4
Power Supply  :  230V Single Phase 60Hz
 RATING CAPACITY:    28,600 BTU/h       AIR FLOW RATE: 883 CFM
INDOOR OUTDOOR
 ENT. TEMP. 
oF (oC)     AMBIENT TEMP. oF (oC)
W B DB 15 25 35 45 55
(-9.4) (-3.9) (1.7) (7.2) (12.8)
TC 28,890 28,790 28,810 28,990 28,870
72 (22.2) SHC 22,560 28,790 22,560 22,730 22,560
59 76 (24.4) SHC 25,980 28,790 25,810 25,980 25,980
(15.0) 80 (26.7) SHC 28,890 28,790 28,810 28,990 28,870
84 (28.9) SHC 28,890 28,790 28,810...

6.  ELECTRICAL DATA
6-1.  Electric Wiring Diagrams
Outdoor Unit CU-3KS19NBU
8FA2-5251-11800-1
62 

Outdoor Unit CU-4KS24NBU
8FA2-5251-11600-1
63 

Outdoor Unit CU-4KS31NBU
8FA2-5251-11400-1
64 

7.  FUNCTIONS
7-1.  Explanation of Functions
The numerical values such as temperature, frequency, time and current in parentheses are an example 
of CU-4KS31NBU and the values are different from the other models.
Control/conditions
INITIAL
Breaker is ON. Power is supplied to the indoor and outdoor unit 
control circuits, however the unit remains stopped.
Positioning of the outdoor unit electric expansion 
valve is performed.
The ON/OFF operation 
button on the remote 
controller is pressed.If automatic...

Control/conditions
COOL
The ON/OFF operation 
button on the remote 
controller is pressed.
The room temperature 
has reached the 
desired temperature.The outdoor unit does not operate for 3 minutes 
even after the breaker is turned ON.
This is in order to stabilize the return of oil to the 
compressor. The outdoor unit starts.
(Compressor and the outdoor fan start.)
When the frequency reaches    Hz, 
frequency increases are stopped for a period 
of    seconds. (Refer to Table 1.)
If the indoor and...

Control/conditions
SENSOR 
DRY
(1/f fluctuation fan)
The ON/OFF operation 
button on the remote 
controller is pressed.The outdoor unit does not operate for 3 minutes 
even after the breaker is turned ON.
This is in order to stabilize the return of oil to the 
compressor. The outdoor unit starts.
(Compressor and the outdoor fan start.)
When the frequency reaches    Hz, 
frequency increases are stopped for a period 
of    seconds. (Refer to Table 1.)
DRY B operation
If the indoor and outdoor temperatures...

< Low Ambient Cooling Operation >
When the mode is switched from cooling opration to low ambient cooling operation,
the compressor is stopped for 150 seconds temporarily.
Outdoor fan speed [ rpm ]
Outdoor air temperature32 °F ( °C )
When the mode has been switched to low ambient cooling operation,
the outdoor fan speed is lowered as the outdoor air temperature falls.
When the outdoor air temperature reaches 57.2 °F (14 °C ) or less during the cooling operation,
the operation mode is switched to low...

7-2.  Protective Functions
The numerical values such as temperature, frequency, time and current in parentheses are an example 
of CU-4KS31NBU and the values are different from the other models.NOTE
7-2-1.  Current Control
The operating current may rise as a result of causes including increasing cooling loads or decreases in power 
voltage. In these cases, the operating frequency is automatically reduced, or operation is stopped, in order to control 
the operating current so that it is (20 A) or less....

Current(A)
Frequency (Hz) Trip
Hz reduction
Hz increase
prohibitHz reduction
Hz increase prohibit
Hz reduction
Hz increase prohibit
(16)
(15.6)
0
(30)Example of operation during cooling
The operating frequency upper limits shown in the figure below are established for frequency reduction and 
increase-prohibit.
(2) Current control
(230)
(223)
(212)Trip
5Hz every 30 sec. reduction
2Hz every 30 sec. reduction
No controlIncrease
prohibit range
(Hz reduction) (°F)
Compressor discharge temperature(194)
Within...