Manufacturer reserves the right to change specifications or designs without notice.
10.2019
ESI (Ultra) Service Manual
54/68
1.
Error definition and method to check:
The low pressure sensor is open or shorted.
The voltage between CN9 pin(1) and (2) is not in the range 0.70~4.50VDC.
CN9
3
IC A/D
input
2
Red
White
GND
1
Black
Measure DC voltage within these pins
2.
Possible causes:
Damaged main control board
Loose connection at port on main control board
Damaged low pressure sensor
Too little refrigerant remains in the system
Display
Low pressure (LP) sensor fault
Check if the low pressure sensor (LP) connected to
CN9
on the
main control board?
NO
YES
NO
YES
YES
NO
Can the pressure transduce measure properly according to
Low
Pressure Sensor Voltage Characteristics C. *NOTE
NO
YES
YES
NO
Replace the main control board
Can the system go into backup running (SEG1 displays digital 2)?
Replace the low pressure sensor
Low pressure at gauge port to malfunction is close to 24.5 psig.
Check any refrigerant blockage
or shortage.
Open the service valves
Are the service valves fully opened?
Reconnect the sensor
5V
Low
pr
es
sur
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se
ns
or