Mitsubishi Electric PURY-80TMU Service Handbook page 72

City multi
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(4) Troubleshooting the major components of the BC controller
1) Pressure sensor
Pressure sensor troubleshooting flow
START
Check pressure sensor, PS1,
PS3, connectors for discon-
nection, looseness, or incor-
rect attachment.
OK?
Yes
Unit running?
No
Yes
Check on the LED monitor dis-
play.
• LPS of outdoor unit.
• HPS of outdoor unit
• PS1, PS3 of BC controller and
confirm the following relationship
HPS > PS1
PS3 > LPS
(puressure calculated value)
OK?
Yes
Stop the unit (compres-
sor OFF).
At least
10 minutes passed since
stopping?
Yes
Check PS1, PS3 on LED
monitor display and confirm
that none of the detected
pressure values is below
0.098MPa (14.2psi).
OK?
Yes
HPS
PS1
PS3
(pressure
calculated
value) (The difference is
less
than
0.098MPa
(14.2psi)
OK?
Yes
No board or pressure
sensor abnormality.
Check that refrigerant piping and
transmission line connections are
in agreement between outdoor
unit and BC controller.
OK?
Yes
Note 1
No
Take corrective action.
Note 2
No
Check that refrigerant pip-
ing and transmission line
connections are in agree-
ment between outdoor
unit and BC controller.
OK?
No
Yes
Note 2
No
LPS
No
Confirm the
following relationship PS1
PS3?
Yes
No
Correct refrigerant
piping and the trans-
mission line.
No
Correct refrigerant
piping and trans-
mission line.
Check for faulty connector on
applicable pressure sensor.
OK?
Yes
Remove the pressure sensor
connector from the board, and
check the pressure.
No
Pressure
0.098MPa
range within 0 to
(14.2psi)
Short connectors 2 and 3 on the
board and check the pressure.
Pressure
of at least 3.14MPa
(455psi) indicated?
Yes
Replace
the
puressure sensor with the
correct pressure sensor, and
confirm it's detected pres-
sure is indicated correctly.
OK?
Yes
Change pres-
sure sensor.
–71–
Note 3
No
Repair faulty connection.
Note 4
No
No
wrong
No
Change board.

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