Indoor Unit Control - Haier MVAH018MV2AA Service Manual

12. Indoor unit control

12.1 Cooling operation
Set temp. in cooling: Ts=set temp. wired controller;
After startup, indoor unit will send the request to outdoor according to the temp. difference between the set temp.
and the room temp.
12.2 Heating operation
Set temp. in heating: Ts=set temp. wired controller + TA correcting value.
After startup, indoor unit will send the request to outdoor according to the temp. difference between the set temp.
and the room temp.
12.3 Dry operation
Room temp. - set temp. > 2°C indoor operation is identical with the cooling operation, and send the cooling mode to
outdoor;
Room temp. - set temp. ≤ 2°C indoor will send the dry signal to outdoor, and indoor fan motor will run at low speed
compulsorily when compressor is running; when room temp. <16°C indoor stops and sends stop signal to outdoor.
In dry operation, the auto mode of indoor fan motor is identical with the cooling mode; EEV control mode is identical
with the cooling operation.
12.4 Fan operation
Indoor fan motor will run at the speed set on the wired controller and sends stop signal to outdoor.
12.5 Abnormal operation
When the requested mode collides with the outdoor mode, the entering earlier will be in prior. After indoor receives
the startup command from wired controller (remote controller), firstly judge the outdoor current mode. If it is normal
mode, the indoor will run as the request of wired controller; if it is abnormal mode, the command can not be
executed, and indoor keeps stop; wired controller displays standby mode (if in remote control type, the buzzer will
sound twice and the remote controller can not receive the signal). Until the outdoor stops or the outdoor mode is
accordant with the requested mode of wired controller (remote controller), the outdoor will work. COOL (including
AUTO COOL), DRY, RECOVERY are regarded as the same mode;
HEAT, RECOVERY are as abnormal mode.
12.6 Fan speed control of indoor fan motor
a. Adjustment by hand
Set high/ mid/ low fan speed as the request.
b. Auto fan speed
Confirm the fan speed as the temp. difference between room temp. TA and the set temp.
c. Anti-cool air control
In heating mode, after compressor startup, the unit will control indoor fan motor state due to the indoor coil temp.
In anti-cool air period, indoor sends pre-heat signal to wired controller; in outdoor defrosting period, indoor fan
motor will stop, and sends defrost signal to wired controller;
After being switched off in heating mode, indoor fan motor will run at low speed and 30 seconds later will stop.
12.7 Set EEV open angle by hand
When being switched off, short connect CN27 to open the valve fully compulsorily for 2 minutes; When being
switched off, short connect CN29 to close the valve fully compulsorily for 2 minutes.
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