Mitsubishi Electric QAHV-N560YA-HPB Service Handbook page 144

[ IX Troubleshooting ]
Low-Pressure Sensor
-2- Low-Pressure Sensor (63LS)
1. Compare the pressure that is detected by the low pressure sensor, and the low pressure gauge pressure to check
for failure.
Error history, temperature and pressure readings of the sensor, and LEV opening
SW2
10 5 6
OFF OFF OFF
Decimal delimiter
A dot will appear when the compressor is in operation.
No dot will appear when the compressor is stopped.
(1) While the sensor is stopped, compare the gauge pressure and the pressure displayed on self-diagnosis LED1.
1) When the gauge pressure is between 0 and 0.098MPa, internal pressure is caused due to gas leak.
2) When the pressure displayed on self-diagnosis LED1 is between 0 and 0.098MPa , the connector may be defective or be
disconnected. Check the connector and go to (4).
3) When the pressure displayed on self-diagnosis LED1 exceeds 10MPa, go to (3).
4) If other than 1), 2) or 3), compare the pressures while the sensor is running. Go to (2).
(2) Compare the gauge pressure and the pressure displayed on self-diagnosis LED1 while the sensor is running.(Com-
pare them by MPa unit.)
1) When the difference between both pressures is within 0.03MPa, both the low pressure sensor and the control board are nor-
mal.
2) When the difference between both pressures exceeds 0.03MPa, the low pressure sensor has a problem. (performance dete-
rioration)
3) When the pressure displayed on the self-diagnosis LED1 does not change, the low pressure sensor has a problem.
(3) Remove the low pressure sensor from the control board to check the pressure with the self-diagnosis LED1 display.
1) When the pressure displayed on the self-diagnosis LED1 is between 0 and 0.098MPa, the low pressure sensor has a problem.
2) When the pressure displayed on self-diagnosis LED1 is approximately 10MPa, the control board has a problem.
When the outdoor temperature is 40°C or less, the control board has a problem.
When the outdoor temperature exceeds 40°C, go to (5).
(4) Remove the low pressure sensor from the control board, and short-circuit between the No.2 and 3 connectors
(63LS:CN63LS) to check the pressure with the self-diagnosis LED1.
1) When the pressure displayed on the self-diagnosis LED1 exceeds 10MPa, the low pressure sensor has a problem.
2) If other than 1), the control board has a problem.
(5) Remove the high pressure sensor (63HS) from the control board, and insert it into the connector for the low pressure
sensor (63LS:CN63LS) to check the pressure with the self-diagnosis LED1.
1) When the pressure displayed on the self-diagnosis LED1 exceeds 10MPa, the control board has a problem.
2) If other than 1), the control board has a problem.
2. Low-pressure sensor configuration
The low pressure sensor consists of the circuit shown in the figure below. If DC5V is applied between the red and the black
wires, voltage corresponding to the pressure between the white and the black wires will be output, and the value of this voltage
will be converted by the microcomputer. The output voltage is 0.039V per 0.098MPa.
Control board side
Vcc Pin 3
Vout Pin 2
GND Pin 1
63LS
1 2 3
HWE1517A
SW3
7 8 9 10
OFF OFF OFF OFF
Pressure 0 - 10 MPa
Vout 0.5 - 4.5 V
0.039 V / 0.098 MPa
1
GND (Black)
2
Vout (White)
3
Vcc (DC5V)(Red)
High pressure and low pressure will appear alternately on the 7-seg-
ment LED at P-second intervals (Default: 3 seconds). See below for
how they are displayed.
Indicates that the high
pressure is displayed
Pressure [MPa] = 2.5 × Vout [V] - 1.25
- 137 -
Indicates that the low
pressure is displayed
GB