Panasonic CS-VZ9SKE Service Manual page 87

15.1.3 IPM (Power Transistor) Prevention Control

Overheating Prevention Control
1 When the IPM temperature rises to 120°C, compressor operation will stop immediately.
2 Compressor operation restarts after 3 minutes the temperature decreases to 110°C.
3 If this condition repeats continuously 4 times within 30 minutes, timer LED will be blinking ("F96" is indicated).

DC Peak Current Control
1 When electric current to IPM exceeds set value of 20 A, the compressor will stop operate. Then, operation
will restart after 3 minutes.
2 If the set value is exceeded again more than 30 seconds after the compressor starts, the operation will
restart after 1 minute.
3 If the set value exceeded again within 30 seconds after the compressor starts, the operation will restart after
1 minute. If this condition repeats continuously for 7 times, all indoor and outdoor relays will be cut off, timer
LED will be blinking ("F99" is indicated).
15.1.4 Compressor Overheating Prevention Control

Instructed frequency for compressor operation will be regulated by compressor discharge temperature. The
changes of frequency are as below.

If compressor discharge temperature exceeds 107°C, compressor will be stopped, occurs 4 times per 20 minutes,
timer LED will be blinking. ("F97" is indicated.)
15.1.5 Low Pressure Prevention Control (Gas Leakage Detection)

Control start conditions
For 5 minutes, the compressor continuously operates and outdoor total current is between 0.75A and 0.95A.
o
During Cooling and Dry operations:
o
Indoor suction temperature - indoor piping temperature is below 4°C.
During Heating operations :
o
Indoor piping temperature - indoor suction is under 5°C.

Control contents
Compressor stops (and restart after 3 minutes).
o
If the conditions above happen 2 times within 20 minutes, the unit will:
o
 Stop operation
 Timer LED blinks and "F91" indicated.
15.1.6 Low Frequency Protection Control 1

When the compressor operate at frequency lower than 24 Hz continued for 240 minutes, the operation frequency
will be changed to 23 Hz for 2 minutes.
15.1.7 Low Frequency Protection Control 2

When all the below conditions comply, the compressor frequency will change to lower frequency.
Indoor intake air (°C)
Outdoor air (°C)
Indoor heat exchanger (°C)
103°C
(107°C)
99°C
(105°C)
96°C
(95°C)
Comp. temperature
(Comp. Discharge temperature)
Temperature, T, for:
Compressor = OFF
Compressor Frequency
Reduce
Compressor Frequency
Maintain
Free
Cooling/Dry
T < 14 or T ≥ 30
T < 13 or T ≥ 38
T < 30
87
92°C
91°C
90°C
(85°C)
Heating
T < 14 or T ≥ 28
T < 4 or T ≥ 24
T ≥ 0