Daikin REYQ-AATJA, Service Manual

Page: 444 / 495

Check SiUS372201EA
437 Part 6 Service Diagnosis
4.9 Pressure Sensor Check
CHECK 12
Voltage Measurement Point of the High Pressure Sensor
Voltage Measurement Point of the Low Pressure Sensor
High Pressure (P
H
)
Low Pressure (P
L
)
Output Voltage V
H
, V
L
Detected Pressure
5.1
–5.1
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
–0.5
–0.5 0 0.5 1 1.5 2 2.5 3 3.5 4
(VDC)
(kg/cm 2 ) (psi) (MPa)
P
H
, P
L
P
H
(MPa) = × V
H
– × 0.5
P
L
(MPa) = × V
L
– × 0.5
P
H
: High pressure (MPa)
P
L
: Low pressure (MPa)
V
H
: Output Voltage (High Side) (VDC)
V
L
: Output Voltage (Low Side) (VDC)
4.15
3.0
4.15
3.0
1.7
3.0 1.7
3.0
1 MPa = 145 psi
40. 8
35.7
30.6
25.5
20.4
15.3
10.2
45.9
51.0
–72.5
725
653
5 8 0
50 8
435
363
290
21 8
145
72.5
0
+5 V
(4)
(3)
(2)
(1)
Red
Black
W hite
X32A
High
press u re
sensor
Microcomp u ter
A/D inp u t
Make meas u rement of DC
v oltage b et w een these w ires.
+5 V
(4)
(3)
(2)
(1)
Microcomputer
A/D input
Make measurement of DC voltage between these wires.
X31A
Red
Black
White
Low
pressure
sensor