Mitsubishi Electric PURY-P120Y(T)HMU-A, Service Handbook

Page: 283 / 387

[
IX
Troubleshooting ]
- 274 - HWE0803A GB
-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.
By configuring the digital display setting switch (SW1) as shown in the figure below, the pressure as measured by the low-
pressure sensor appears on the LED1 on the control board.
(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 [14psi], internal pressure is caused due to gas leak.
2) When the pressure displayed on self-diagnosis LED1 is between 0 and 0.098MPa [14psi], 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 1.7MPa [247psi], 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 [psi] unit.)
1) When the difference between both pressures is within 0.03MPa [4psi], both the low pressure sensor and the control board are
normal.
2) When the difference between both pressures exceeds 0.03MPa [4psi], the low pressure sensor has a problem. (performance
deterioration)
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 [14psi], the low pressure sensor has a
problem.
2) When the pressure displayed on self-diagnosis LED1 is approximately 1.7MPa [247psi], the control board has a problem.
Œ When the outdoor temperature is 30°C [86°F] or less, the control board has a problem.
Œ When the outdoor temperature exceeds 30°C [86°F], go to (5).
(4) Remove the low pressure sensor from the control board, and short-circuit between the No.2 and 3 connectors
(63LS:CN202) to check the pressure with the self-diagnosis LED1.
1) When the pressure displayed on the self-diagnosis LED1 exceeds 1.7MPa [247psi], the low pressure sensor has a problem.
2) If other than 1), the control board has a problem.
(5) Remove the high pressure sensor (63HS1) from the control board, and insert it into the connector for the low pres-
sure sensor (63LS) to check the pressure with the self-diagnosis LED1.
1) When the pressure displayed on the self-diagnosis LED1 exceeds 1.7MPa [247psi], 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 0.173V per 0.098MPa [14psi].
The pressure sensor on the body side is designed to connect to the connector. The connector pin number on the body side
is different from that on the control board side.
Body side Control board side
Vcc Pin 1 Pin 3
Vout Pin 2 Pin 2
GND Pin 3 Pin 1
1 2 3 4 5 6 7 8 9 10
ON
SW1
0
0.2 [29]
0.4 [58]
0.6 [87]
0.8 [116]
1.0 [145]
1.2 [174]
1.4 [203]
1.6 [232]
1.8 [261]
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage (V)
Pressure
(MPa [psi])
Connector
63LS
1 2 3
1
2
3
GND (Black)
Vout (White)
Vcc (DC 5 V)(Red)
Pressure 0 ~ 1.7 MPa [247psi]
Vout 0.5 ~ 3.5 V
0.173 V / 0.098 MPa [14 psi]