Domestic Air Conditioner 
22
 
 
      TEC×TAˉ 
Among which: C:TA˘0ćˈC=0.8 
              TA0ćˈC=0.6 
For area prone to frost, the value is set at 6 when unit leaves the factory. 
Defrosting entry temperature control -15 C×TAć ˉ-5ć 
 
 
Defrosting Time Interval 
time interval between two defrosting cycles is 45 minutes. 
Defrosting Operation 
When defrosting begins, compressor will stop for one minute, external fan is running    and 50s later, 
four-way valve will be off.   
When compressor starts, external fan will be off, compressor will run at 28Hz for 60s then run at 60Hz 
for 60s and then move on to target frequency of 88Hz.   
During defrosting, compressor current and air discharge overheat protection features are effective. 
During defrosting, if compressor shuts down due to activation of protection feature or due to 
malfunction, it will resume after 3 minutes. In the unit is still within defrosting cycle, it will resume 
defrosting and startup of compressor will be based on the rule for defrosting startup. (The unit will exit 
defrosting mode and handle fault in the event of 3 consecutive restart failures.) 
On entering defrosting, it must guarantee that compressor will operate for a minimum of 2 minutes in 
defrosting mode before exit. 
 
 
Defrosting Exit Condition 
When one of the following conditions is met, defrosting operation will be switched to heating 
operation. 
˄1˅:Temperature of outdoor heat exchanger exceeds10  for 80s continuouslyć  
˄2˅: Temperature of outdoor heat exchanger exceeds 15  for 5s continuouslyć  
˄3˅:Defrosting operation continues for 18 minutes.   
 
 
When defrosting exit conditions are met, the unit will operate as follows   
Compressor stops and external fan starts, 50s later, four-way valve will be on, 60s later, compressor 
will operate as per startup process. 
 
5.2.5 PTC Output Control 
When outdoor unit is energized, PTC output value is 0, 10s later, output value is 1. 
 
 
5.2.6 System Protection Function 
 
5.2.6.1 3 minutes stand-by time 
Time interval between compressor shutdown and restart is set at 3 minutes to ensure that compressor 
will only restart after 3-minute shutdown and initial energization valves are turned on to adequate 
opening position after being fully turned off.