Fisher FSAI-Pro-91AE2 Service Manual page 30

Preheating release condition:
If T4＞5℃ or the compressor starts running, the preheating function will stop.
8.3.8 Sensor protection at open circuit and breaking disconnection.
When there's one temperature sensor in malfunction, the air conditioner will display error code and will
not stop immediately, to avoid the case that the air conditioner is in urgent need.
Fault temp. Operation in cooling,
sensor drying and fan only mode
T1
Run supposed T1=26℃
high fan speed
T2 Normal
T3 Run with compressor
frequency≤F14
T4
Run supposed T4=50℃
TP
Run supposed T4=50℃
8.3.9 Refrigerant leakage detection
This function is only active in cooling mode. It can better prevent the compressor being damaged
by refrigerant leakage or compressor overload.
Open condition:
Define the evaporator coil temp.T2 of the compressor just starts running as Tcool.
In the beginning 5 minutes after the compressor starts up, if T2 ＜Tcool－2℃ does not
continuous 4 seconds and this situation happens 3 times, the display area will show "EC" and AC will
turn off.
8.3.10 Zero crossing detection error protection(except FSAIF-Pro-181AE2)
If AC detects time interval is not correct for continuous 240s, the unit will stop and the LED will display
the failure. The correct zero crossing signal time interval should be between 6-13ms.
Operation in heating mode
Run supposed T1=26℃ medium fan speed
During the first 1 minute of compressor operation, indoor
fan shuts off. After that, indoor fan runs at medium fan
speed for 1 minute and then resume to the setting fan
speed.
3 minutes' defrosting every 40 minutes when T4<7℃; 2
minutes' defrosting every 90 minutes when T4≥7℃.
Run supposed T4=15℃
Run supposed T4=15℃
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keep