Haier AS25THMHRA-C, Service Manual

Page: 227 / 537

Functions and control
18
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 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
09K Abnormal stop
107
Decreasing the frequency rapidly 1HZ/second
102
Decreasing the frequency slowly (1HZ/10seconds)
98
The frequency doesn’t change.
95
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.
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.