Haier 1U50MEMFRA-C Service Manual page 19

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
value of the middle
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TTC（℃）
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108
104
102
100
93
TTC>=110℃ lasts for 20 seconds. Overheating protection of air-blowing, alarm malfunction to the
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indoor, others don't last.
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
h time: continuously sampling for 8 times, then order them and take the mean
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2 values), take the mean value.
Decreasing the frequency rapidly（1HZ/second）
Decreasing the frequency slowly (1HZ/10seconds)
The frequency doesn't change.
Increasing the frequency (1HZ/10second)
Increasing the frequency（1HZ/1second）
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Abnormal stop
17
Functions and control
Domestic air conditioner