Fisher FSFIF-121AE2, Service Manual

Page: 121 / 157

Electrical Control Function
Electrical Control System 117
1. Electrical Control Function
1.1 Definition
T1: Indoor room temperature
T2: Coil temperature of indoor heat exchanger middle.
T2B: Coil temperature of indoor heat exchanger outlet.
T3: Coil temperature of condenser
T4: Outdoor ambient temperature
T5: Compressor discharge temperature
1.2 Main Protection
1.2.1 Time delay at restart for compressor.
1.2.2 Temperature protection of compressor discharge
When the compressor discharge temp. is getting higher, the running frequency will be limited as below rules:
12K 18~60K
T 5
C o m p re s s o r o ff
F re q u e n c y lim it1
F
E
D
C
F re q u e n c ie s in c re a se slo w ly
B
N o rm a l
A
F re q u e n c y h o ld in g
F re q u e n c y lim it2
T 5
C o m p re s so r o ff
F re q u e n cy lim it
N o rm a l
F re q u e n cy h o ld in g
1.2.3 Sensor protection at open circuit and breaking disconnection.
1.2.5 Indoor fan delayed open function
When the unit starts up, the louver will be active immediately and the indoor fan will open 7s later.
If the unit runs in heating mode, the indoor fan will be also controlled by anti-cold wind function.
1.2.6 Fan speed is out of control
For console:
When indoor fan speed keeps too low (300RPM) for certain time, the unit will stop and the LED will display
the failure.
For other models:
When indoor fan speed keeps too low (lower than 300 RPM) for 50s, the indoor fan will shut off and restart
30s later, if protection happened 3 times when fan motor restart continuously, the unit will stop and the LED
will display the failure.