Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 94

8-8-3. Low pressure sensor
■ The methods of comparing the low pressure sensor measurement and gauge pressure
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.
SW1
ON
OFF
1 2 3 4 5 6 7 8
The black square (■) indicates a switch position.
1. While the outdoor unit is stopped, compare the gauge pressure and the pressure displayed on the self-diagnosis
LED1, 2.
• When the gauge pressure is between 0 and 0.098 MPaG [14 psig], internal pressure is caused due to gas leak.
• When the pressure displayed on the self-diagnosis LED1, 2 is between 0 and 0.098 MPaG [14 psig], the connector
may be faulty or be disconnected. Check the connector and go to the method 4.
• When the outdoor temperature is 30°C [86°F] or less, and the pressure displayed on the self-diagnosis LED1, 2
exceeds 1.7 MPaG [247 psig], go to the method 3.
• When the outdoor temperature exceeds 30°C [86°F], and the pressure displayed on the self-diagnosis LED1, 2
exceeds 1.7 MPaG [247 psig], go to the method 5.
• If other than listed above, compare the pressures while the sensor is running. Go to the method 2.
2. Compare the gauge pressure and the pressure displayed on the self-diagnosis LED1, 2 after 15 minutes have
passed since the start of operation. (Compare them by MPaG [psig] unit.)
• When the difference between both pressures is within 0.2 MPaG [29 psig], both the low pressure sensor and the
control board are normal.
• When the difference between both pressures exceeds 0.2 MPaG [29 psig], the low pressure sensor has a problem.
(performance deterioration)
• When the pressure displayed on the self-diagnosis LED1, 2 does not change, the low pressure sensor has a prob-
lem.
3. Remove the low pressure sensor from the control board to check the pressure with the self-diagnosis LED1, 2.
• When the pressure displayed on the self-diagnosis LED1, 2 is between 0 and 0.098 MPaG [14 psig], the low pres-
sure sensor has a problem.
• When the pressure displayed on the self-diagnosis LED1, 2 is approximately 1.7 MPaG [247 psig], the control
board has a problem.
• When the pressure displayed on the self-diagnosis LED1, 2 exceeds 1.7 MPaG [247 psig], the low pressure sensor
has a problem.
• If other than listed above, the control board has a problem.
4. Remove the high pressure sensor (63HS) from the control board, and insert it into the connector for the low pressure
sensor (63LS) to check the pressure with the self-diagnosis LED1, 2.
• When the pressure displayed on the self-diagnosis LED1, 2 exceeds 1.7 MPaG [247 psig], the control board has a
problem.
• If other than listed above, go to the method 2.
■ Low pressure sensor configuration (63LS)
The low pressure sensor consists of the circuit shown in the figure below. If 5 V DC 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 microprocessor. The output voltage is 0.173 V per 0.098 MPaG [14 psig].
Note:
• 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
Vcc Pin 1
Vout Pin 2
GND Pin 3
RD
WH
Vout
BK
63HS
3–1: 5 V (DC)
2–1: Output Vout (DC)
OCH790 _94
Control board side
Pin 3
Pin 2
Pin 1
OUTDOOR MULTI CONTROLLER
CIRCUIT BOARD
Pressure: 0–5.0 MPaG [725 psig]
5 V DC
Vout: 0.5–4.5 V
3
0.078 V/0.098 MPaG [14 psig]
2
MICRO
PROCESSOR
1
GND
Vout (V)
3.5
2.0
0.5
0.85 1.7
123 247
PRESSURE
(MPaG)
(PSIG)