FUNCTION AND CONTROL
a.Under AUTO mode, if Tamb.≥Tpreset is detected, the unit will select to run under cooling mode, in which case implicit preset temperature is 77°F; if Tamb.≤Tpreset 28°F, the compressor will stop, the outdoor fan will stop with a time lag of 1 minute, and the indoor fan will run at preset speed; and if
b.Under AUTO mode, if Tamb. ≤Tpreset +36°F is detected, the unit will select to run under heating mode, in which case
implicit preset temperature is 64°F; if Tamb.≥Tpreset 41°F, the compressor will stop, the outdoor fan will stop with a time lag
of 1 minute, and the indoor fan will run under the mode of residue heat blowing; and if Tpreset +36°F < Tamb.< Tpreset +41°F, the unit will remain at its original state. The
c.Under AUTO mode, if 68°F< Tamb.< 77°F, the unit will remain at its original state. 2.Protection
a. In cooling operation, protection is the same as that under the cooling mode; b. In heating operation, protection is the same as that under the heating mode;
c. When ambient temperature changes, operation mode will be converted preferentially. Once started, the compressor will remain unchanged for at least 6 minutes.
(6) Common Protection Functions and Fault Display under COOL, HEAT, DRY and AUTO Modes
Overload protection
Ttube : measured temperature of outdoor heat exchanger undercooling mode; and measured temperature of indoor heat exchanger under heating mode.
1) Cooling overload
a. If Ttube ≤106°F, the unit will return to its original operation state. b. If T tube ≥131°F, frequency rise is not allowed.
c. If T tube ≥136°F, the compressor will r unat reduced frequency.
d. If T tube ≥144°F, the compressor will stop and the indoor fan will run at preset speed.
2) Heating overload
a. If Ttube ≤106°F, the unit will return to its original operation state. b. If T tube ≥131°F, frequency rise is not allowed.
c. If T tube ≥136°F, the compressor will run at reduced frequency.
d. If T tube≥144°F, the compressor will stop and the indoor fan will blow residue heat and then stop. 
Exhaust temperature protection of compressor
If exhaust temperature≥208°F, frequency is not allowed to rise.
If exhaust temperature≥217°F, the compressor will run at reduced frequency. If exhaust temperature≥230°F, the compressor will stop.
If exhaust temperature ≤194°F and the compressor has stayed at stop for at least 3 minutes, the compressor will resume its operation.
Communication fault
If the unit fails to receive correct signals for durative 3 minutes, communication fault can be justified and the whole system will stop.
Module protection
Under module protection mode, the compressor will stop. When the compressor remains at stop for at least 3 minutes, the compressor will resume its operation. If module protection occurs six times in succession, the compressor will not be started again.
Overload protection
If temperature sensed by the overload sensor is over 239°F, the compressor will stop and the outdoor fan will stop with a time lag of 30 seconds. If temperature is below 203°F, the overload protection will be relieved.
If voltage on the DC bus is below 150V or over 420V, the compressor will stop and the outdoor fan will stop with a time lag of 30 seconds. When voltage on the DC bus returns to its normal value and the compressor has stayed at stop for at least 3 minutes, the compressor will resume its operation.
Faults of temperature sensors
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