– 124 –
Since current flows at point only when U+ transistor is ON, the current waveform at point becomes intermittent
waveform as shown in Fig. 3-3. Since current at point is approximately proportional to the input current of the air
conditioner, input current is controlled by using DC current (Id) detection resistor.
Simplified check of power module (Lighting mode when operated with compressor leads disconnected)
(1) Disconnect connector of 3-pole (WHT, YEL, RED) lead wire connecting to compressor located at the lower
part of electric parts box.
(2) Set to compressor operation state (other than FAN mode) and press Start/stop switch of remote control.
(3) If normal operation continues for more than 1 minute (LD303 lights), power module is considered normal.
Refer to other item (troubleshooting on page 200) for independent checking of power module.
If power module is detective, self diagnosis lamps on the main P.W.B. may indicate as shown below:
<Reference>
Table 3-1
Ip (peak current cut)
LD301
Blinks 2
times
Blinks 3
times
Blinks 4
times
LD301
LD301
Self-diagnosis
Self-diagnosis lamp
and mode
Abnormal low speed
rotation
Switching failure
U
V
W
U
V
W
U
V
W
A
B
R24
Fig. 3-4 Power module circuit (U+ is ON, V- is ON)
Fig. 3-5
DC current (Id)
detection resistor
320-360V
System Power module 2
U coil
V coil
W coil
DC compressor
motor
N
Terminal Boards
P.W.B. (Main)
LD303
Self Diagnosis Lamps
Service
Switch
Reactor
SPM2
Smoothing Capacitors
Diode Stack
LD302
LD301
CN12
CN16
CN18
CN14
CN13
CN11
CN5
CN10
CN9
CN8
CN15
CN2
CN7
YEL
BLU
RED
BRN
GRN1
WHT
BLK
GRN2
RED
WHT