MAXA BDS28A, Technical Manual

Page: 13 / 36

13
7.2.3.3 Protection function
♦
Anti-cold – wind protection
In HEAT mode, in order to prevent the indoor unit from blowing out cold wind, each time the compressor starts, the indoor
fan will delay 3 minutes after the compressor to run at the latest and it can adjust fan speed automatically when
temperature is low.
♦
 Overcurrent protection
Overcurrent protection is the same with that in COOL mode.
Protection
♦ Cold air prevention
The unit is started under heating mode (the compressor is ON):
①
In the case of T
indoor amb.
< 24°C: if T
tube
≤ 40°C and the indoor fan is at stop state, the indoor fan will begin to run at low
speed with a time lag of 2 minutes. Within 2 minutes, if T
tube
> 40°C, the indoor fan also will run at low speed; and after
1-minute operation at low speed, the indoor fan will be converted to operation at preset speed. Within 1-minute low speed
operation or 2-minute non-operation, if T
tube
> 42°C, the fan will run at present speed.
②
In the case of T
indoor amb.
≥ 24°C: if T
tube
> 42°C, the indoor fan will run at low speed, and after one minute, the indoor fan
will be converted to preset speed. Within one-minute low speed operation, if T
tube
> 42°C, the indoor fan will be converted to
preset speed.
Note : T
indoor amb
. indicated in
①
and
②
refers to, under initially heating mode, the indoor ambient temperature before the
command to start the compressor is performed according to the program, or after the unit is withdrawn from defrost, the
indoor ambient temperature before the defrost symbol is cleared.
♦ Total current up and frequency down protection
If the total current I
total
≤ W, frequency rise will be allowed; if I
total
≥ X, frequency rise will not be allowed; if I
total
≥ Y, the
compressor will run at reduced frequency; and if I
total
≥ Z, the compressor will stop and the outdoor fan will stop with a time
lag of 30s.
7.2.4 Fan Mode
Under the mode, the indoor fan will run at preset speed and the compressor, the outdoor fan, the four-way valve and the
electric heater will stop.
7.2.5 AUTO Mode
①
Working conditions and process of AUTO mode
Under AUTO mode, standard cooling temperature T
set
is 25°C and standard heating temperature T
set
is 20°C.
a) Once energized, if T
amb.
≤ 22°C, the unit will be started under heating mode; if 23°C< T
amb.
< 25°C, the unit will run under
fan mode and the run indicator will be bright; and if T
amb.
≥ 25°C, the unit will be started under cooling mode.
b) Under AUTO mode, if T
amb.
≥ T
set
is detected, the unit will select to run under cooling mode, in which case implicit set
temperature is 25°C; if T
amb.
≤ T
preset
- 2°C, the compressor will stop, the outdoor fan will stop with a time lag of 1 minute, and
the indoor fan will run at set speed; and if T
set
- 2°C< T
amb.
< T
set
, the unit will remain at its original state.
c) Under AUTO mode, if T
amb.
≤ T
set
+2°C is detected, the unit will select to run under heating mode, in which case implicit
preset temperature is 20°C; if T
amb.
≥ T
set
+ 5°C, the compressor will stop, the outdoor fan will stop with a time lag of 1
minute, and the indoor fan will run under the mode of residue heat blowing; and if T
set
+2°C< T
amb.
< T
set
+ 5°C, the unit will
remain at its original state.
d) Under AUTO mode, if 23°C < T
amb.
< 25°C, the unit will remain at its original state.