Description Of Operation Circuit - Carrier 42NQV009E Service Manual

8-2. Description of Operation Circuit

•
Turning [ON] the breaker flashes the ON/OFF
lamp. (1Hz)
This is the display of power-ON (or notification of
power failure).
•
When pushing [ ] button of the
remote control, receive sound is issued from the
main unit, and the next operations are performed
together with opening the vertical air flow louvers.
8-2-1. Cooling operation
•
Once the setting is made, the operation mode is
memorized in the microcomputer so that the same
operation can be effected thereafter simply by
pushing [ ] button.
•
A cooling operation signal is transmitted to
outdoor unit.
•
The outdoor unit controls the outdoor fan relay
R01, R02 and R03, and the compressor motor
speed according to the operation command signal
sent from the indoor unit.
•
When [FAN] button is set to AUTO, the indoor fan
motor operates as shown in Fig. 8-2-1. When
[FAN] button is set to LOW , MED or
HIGH, the motor operates with a constant
air flow.
°C
+3
+2.5
+2
+1.5
+1
+0.5
Set
0
temp.
−0.5
NOTE :
*1: Calculated from difference in motor speed of M+
and L, and controlled.
Fig. 8-2-1 Setting of air flow [Fan AUTO]
(1) Cooling capacity control
• The cooling capacity and room temperature
are controller by changing the compressor
motor speed according to both the difference
between the temperature detected by the room
temperature sensor and the temperature set by
[ ] or [ ] button and also any change in room
temperature.
(2) Prevent-freezing control
If temperature of indoor heat exchanger detected
by the indoor heat exchanger sensor is 5°C lower,
compressor motor speed is gradually lowered to
prevent freezing of the indoor heat exchanger. If
temperature is 7°C or higher, return the operation
to the above item (1).
(3) Current release control
The input current of compressor and outdoor fan
motor (Precisely inverter main circuit control
section) which occupy most of air conditioner input
is detected by the outdoor current sensor, and
compressor motor speed is gradually
it input current exceed the current value
determined in each zone as show in
fig 8-2-2 so that the input current does not
exceed the set value.
In case that the current lowered by approx
0.5 A than each value, return to above
item (1).
38NYV009 / 38NYV012E
M+
*1
5.2 / 6.8
*1
*1
4.7 / 6.3
L
In normal
operation
– 27 –
FILE NO. SVM-07018
Comp. motor
speed down
Comp. motor
speed keep
Normal control
Fig. 8-2-2