Functions and control
17 Domestic air conditioner 
7.1.4 Four way control 
For the details of defrosting four-way valve control, see the defrosting process. 
Four way working in other ways: 
Under the mode of heating, open the four-way valve, when the compressor is not started or changed to 
non-heating mode, make sure the compressor is stoped for 2 minutes, and then close the four-way valve. 
7.1.5 Protection function 
7.1.5.1 TTC high temperature-preventing protection 
Once the machine is started, it can run TTC(air-blowing temp) overheating protection of air-blowing, 
but air-blowing sensor malfunction must alarm after 4 minutes during which the compressor is started 
(during the course of self-detection, there’s no such limitation)   
Sensor detection methods: 100 times (one cycle of procedure run is one time, and about 5ms, 
detection method for eac
●
h time: continuously sampling for 8 times, then order them and take the mean 
value of the middle 
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2 values), take the mean value. 
TTC(℃) 
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 Abnormal stop 
108
 Decreasing the frequency rapidly(1HZ/second) 
104
 Decreasing the frequency slowly (1HZ/10seconds) 
102
 The frequency doesn’t change.  
100 
 Increasing the frequency (1HZ/10second) 
93
 Increasing the frequency(1HZ/1second) 
TTC>=110℃
●
 lasts for 20 seconds. Overheating protection of air-blowing, alarm malfunction to the 
indoor, others don’t last.
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7.1.5.2 TC high temperature-preventing control of the indoor heating unit: 
Tpg_indoor is the highest value of the effective indoor unit (start it and it is in accord with the running