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7) Discharge Temperature Control
The following control is performed to prevent the discharge temperature from rising abnormally in order to
protect the inverter compressor. In accordance with the temperature of the discharge sensor TD, such controls
are performed as to limiting the increase of inverter frequency, decreasing it or halting operation of the
compressor.
TD (discharge)
111
106
100
95
90
* If the discharge temperature exceeds 111 , operations of the compressor are halted and then
restarted 3 minutes later.
If this start/stop activity is repeated 4 times consecutively, the alarm "P03" (abnormal discharge
temperature) occurs.
8) Defrosting Control
This control function removes frost that has adhered to the outdoor heat exchanger during the heating operation.
The control is performed to prevent the deterioration of the heating capabilities attributed to the adherence of
frost, and to prevent the crack or crush of pipes attributed to the accretion of ice.
The following control is performed in accordance with the external temperature and the outdoor heat exchanger
temperature sensor (C1).
Overall Flow Chart of Defrosting Control
Normal heating operation
Has frost adherence been
detected?
Yes (detected)
Has more than 25 minutes
(heating mask time) elapsed?
Yes (elapsed)
Defrosting operations commenced
Have the conditions for ending
defrosting been satisfi ed?
Yes (satisfi ed)
Heating operation resumed
Outdoor unit operation halted
Frequency decreased
Frequency increases prevented
Frequency increased slower than usual
Normal (no control)
Heating
No
operation
continued
Heating
No
operation
continued
Defrosting
No
operation
continued
Frost adherence detection
• If the following conditions are satisfied during heating
operations, it is regarded as "frost adherence is
detected".
• Frost adherence detection is performed in accordance
with the outdoor air temperature (TO) and the outdoor
heat exchanger temperature sensor (C1).
*
However, frost adherence detection is not performed
for the first fifteen minutes of compressor operations
in the normal heating mode.
• Frost adherence detection conditions
(a) With the outdoor air temperature (TO) being -13
or above, the frost adherence condition shown
below are satisfied for whether 3 consecutive
minutes or a total of 60 intermittent minutes, or
the outdoor heat exchanger temperature sensor
(C1) remains -18
seconds.
Outdoor heat exchanger temperature sensor (C1) (°C)
-13
(b) With the outdoor air temperature (TO) being less
than -13 , the outdoor heat exchanger
temperature sensor (C1) remains less than or
equal to outdoor air temperature (TO) - 5
consecutive seconds.
(c) With the outdoor heat exchanger temperature
sensor (C1) being less than -3 , a total of 90
minutes has elapsed (defrosting carried out
periodically in accordance with the time).
4-5
or below for 20 consecutive
Y
Outdoor air temperature (TO) (°C)
0
10
X
-3
-8
Defrosting condition zone
-19.4
for 20
4
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