Heating Mode(Heat Pump Units) - Century COMFORT-AIRE VMH-SG Series Service Manual

For AC fan motor units:
3.3.3 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.
3.3.4 Condenser Temperature Protection
When the condenser temperature exceeds a configured
value, the compressor ceases operation.
3.3.5 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.
3.4

Heating Mode(Heat Pump Units)

3.4.1 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.
3.4.2 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
• 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)
 Product Features
Product Features 5
Service Manual - VMHxxSG
5 
ΔTE1=0
ΔTE1=19°C-T1
(34.2°F-T1)
ΔTE1=4°C(7.2°F)