104
16.4.18 F91 (Refrigeration Cycle Abnormality)
Malfunction Decision Conditions
During cooling, compressor frequency = Fcmax.
During cooling and heating operation, running current: 0.65 A < I < 1.65 A.
During cooling, indoor intake - indoor pipe < 4°C.
Malfunction Caused
Refrigerant shortage (refrigerant leakage).
Poor compression performance of compressor.
2/3 way valve closed.
Detection error due to faulty indoor intake air or indoor pipe temperature sensors.
Troubleshooting
For safety reason and to prevent component
breakdown, always switch off the power
before remove and connect the component.
YES
YES
YES
NO
NO
NO
NO
YES
70
60
50
40
30
20
-10
0
10
20
30
40
50
10
0
R
e
si
st
an
c
e
(k
Ω
)
Sensor (Thermistor)
Characteristics
Pipe temp. Sensor
Intake Air Temp. Sensor
1
2
1
2
Temperature (°C)
When F91 indication happens
Check the indoor air intake and pipe
temperature sensors.
Does it conform to the sensor
characteristic chart?
2/3-way valve opened?
Oil oozing out from the 2/3 way valve?
Capillary tube or dryer clogged?
Refrigerant cycle abnormality error again?
Charge for a specified amount of fresh
refrigerant.
Check for gas leaking.
Replace the indoor intake air or pipe
temperature sensor
Repair the pipe flare or union nuts.
Reclaim and recharge refrigerant.
Replace outdoor unit PCB &
compressor
Open 2/3 way valve
Replace the capillary tube or dryer.
Procedure complete
