Haier Unitary smart series Service Manual page 136

TD 55 , +1 degree / 2 minutes, and plus to 0 degree gradually
Heating Td 35
35
TD 40 , -1 degree / 2 minutes, and reduce to 0 degree gradually
7.2.4 4-way valve control
The 4-way valve control in defrosting: refer to the defrosting procedure.
4-way valve control in other modes:
In heating mode, 4-way valve will open in 10 seconds before compressor starts up. When
compressor not startup or in non-heating mode, 4-way valve will close to ensure the compressor
has stopped for at least 2 minutes.
7.2.5 Outdoor defrosting control
A. Enter condition
In heating mode, compressor is running for 10 minutes contineously, or has run for 45 minutes
in all (when defrosting is over or entering the cooling mode, the counter will be cleared), by
measuring the defrosting sensor TE and outdoor ambient temp. sensor TA, if for 2 minutes the below
conditions can be met contineously, system will enter defrosting mode:
Selct as follow according to the data of EEPROM:
Connection choosing
( )
Easy to deforst: select H, uneasy to deforst: select L, set in M when out of the factory.
Entering defrost temperature: -15
B. Defrost interval time
When the value of C TA
45 minutes.
When the value of C TA
65 minutes.
C. Defrost procedure
At the beginning of defrost, compressor will firstly stop for 1 mintue, outdoor fan runs, and 50
seconds later, 4-way valve is OFF.
When compressor starts up, outdoor motor stops, compressor stay at 60Hz for 60 seconds,
then compressor frequency will go up to the target frequency 88Hz.
In defrosting, the compressor current, compressor discharging protections are valid. If in
defrosting, compressor stops because of the protection or the failure, 3 minutes later, it will resume,
and if it still in defrosting time, the unit will still defrost. The compressor will start up due to the
principle of startup in defrosting. If contineously the compressor can not start up for 3 times, the unit
will deal with the malfunction and quit the defrosting. If in defrosting there is failure, the failure time
will not be included in the defrosting time.
In defrosting, only after the compressor min. running time is over 2 minutes, the system can
quit the defrosting.
D. Quit condition
In any of the below conditions can be met, the defrosting mode will turn into heating operation.
(1): Outdoor heat exchanger temperature is over 10
(2): Outdoor heat exchanger temperature is over 14
+1 degree / 2 minutes
Td 40 , keep the angle
TE C TA
Here in: C: TA 0 , C=0.8
TA 0 , C=0.6
L
10
C TA
is in the range of -15
is in the range of C TA
a__
M
7
-5
C TA
<-15 , two defrosting interval is
for 80 seconds contineously.
for 20 seconds contineously.
-136-
^ a`
Max. +5
H
6
, two defrosting interval is
a`