Sanyo Big PACi 18 Series Technical Data & Service Manual page 208

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)
115
105
100
95
80
* If the discharge temperature exceeds 115
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 satisfied?
Yes (satisfied)
Heating operation resumed
Outdoor unit operation halted
Frequency decreased
Frequency increases prevented
Frequency increased slower than usual
Normal (no control)
, operations of the compressor are halted and then
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).
*
Heating
No
operation
continued
Frost adherence detection conditions
(a)
Heating
No
operation
continued
(b)
Defrosting
No
operation
continued
(c)
4-5
However, frost adherence detection is not performed
for the first 15 minutes of compressor operations in
the normal heating mode.
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 or below for 20 consecutive seconds.
Outdoor heat exchanger temperature sensor (C1) (°C)
Y
Outdoor air temperature (TO) (°C)
-13 0
-3
-8
Defrosting condition zone
-19.4
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
seconds.
With the outdoor heat exchanger temperature
sensor (C1) being less than -3
minutes has elapsed (defrosting carried out
periodically in accordance with the time).
10
X
for 20 consecutive
, a total of 90
4