Haier AS25THMHRA-C Service Manual page 489

If |SH|≥3,and △SH=0, 10s/ 1 step.
If 3≥|SH|≥0, 30s/ 1 step.
△SH= current SH- last SH
SH= Ts (suction temp)-Tc1 (indoor coil temp)-Tsh (fixed data, depend on different models, -1~2)
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
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 each time: continuously sampling for 8 times, then order them and take the mean
value of the middle 2 values), take the mean value.
TTC（℃）
107
104
100
98
93
TTC>=1 07℃ 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 state). TC=indoor coil temp.
The indoor heat exchanger sensor tests the temperature of the indoor heat exchanger. If the
temperature is higher than 63℃, decrease the rotate speed of the compressor and do the high
temperature-preventing protection of the indoor heat exchanger; if the temperature of the indoor heat
exchanger is lower than 45℃, recover to the normal control.
-blowing sensor malfunction must alarm after 4 minutes during which the
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Abnormal stop
Decreasing the frequency rapidly（1HZ/second）
Decreasing the frequency slowly (1HZ/10seconds)
The frequency doesn't change.
Increasing the frequency (1HZ/10second)
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Increasing the frequency
（1HZ/1second）
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17 Domestic air conditioner
Functions and control
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