Heating Mode(Heat Pump Units) - Fisher FSAIF-CP-91AE3 Technical Manual

When the condenser temperature exceeds a configured
value, the compressor ceases operation.
1.5.5 Evaporator Temperature Protection
• Off: Compressor stops.
• Decrease: Decrease the running frequency to the lower
level per 1 minute.
• Hold: Keep the current frequency.
• Resume: No limitation for frequency.
1.6

Heating Mode(Heat Pump Units)

1.6.1 Compressor Control
1) Reach the configured temperature
• If the following conditions are satisfied, the
compressor ceases operation.
• Calculated frequency(fb) is less than minimum limit
frequency(FminH).
• Compressor runs at FminH more than 10 minutes.
• T1 is higher than or equal to Tsc+ HDIFTEMP2.
Note: HDIFTEMP2 is EEPROM setting parameter. It is 2°C
usually.
• If one of the following conditions is satisfied, not
judge protective time.
• Compressor running frequency(fr) is more than test
frequency(TestFre).
• When compressor running frequency is equal to
test frequency, T4 is more than 15°C or T4 fault.
• Change setting temperature.
• Turbo or sleep function on/off.
2) When the current is higher than the predefined safe
value, surge protection is activated, causing the
compressor to cease operations.
1.6.2 Indoor Fan Control:
1) In heating mode, the indoor fan operates continuously.
The fan speed can be set to 1%-100%, or mute.And
the anti-cold wind function has the priority.
• Anti-cold air function
 Page 30 
• The indoor fan is controlled by the indoor
temperature T1 and indoor unit coil temperature
T2.
T1 ≥ 19°C(66.2°F)
15°C(59°F) ≤ T1 < 19°C(66.2°F)
T1<15°C(59°F)
2) Auto fan
• Rise curve
• When T1-Tsc is higher than -1.5°C, fan speed
reduces to 80%;
• When T1-Tsc is higher than 0°C, fan speed reduces
to 60%;
• When T1-Tsc is higher than 0.5°C, fan speed
reduces to 40%;
• When T1-Tsc is higher than 1°C, fan speed reduces
to 20%.
• Descent curve
• When T1-Tsc is lower than or equal to 0.5°C, fan
speed increases to 40%;
• When T1-Tsc is lower than or equal to 0°C, fan
speed increases to 60%;
• When T1-Tsc is lower than or equal to -1.5°C, fan
speed increases to 80%;
• When T1-Tsc is lower than or equal to -3°C, fan
speed increases to 100%.
1.6.3 Outdoor Fan Control:
• The outdoor unit will be run at different fan speed
according to T4 and compressor running frequency.
• For different outdoor units, the fan speeds are
different.
1.6.4 Defrosting Mode
• The unit enters defrosting mode according to changes
in the temperature value of T3, T4 as well as the
compressor running time.
• In defrosting mode, the compressor continues to run,
the indoor and outdoor motor will cease operation,
the defrost light of the indoor unit will turn on, and
the " " symbol is displayed.
ΔTE1=0
ΔTE1=19°C-T1
(34.2°F-T1)
ΔTE1=4°C(7.2°F)