Mitsubishi Electric PQRY-P200YEM-A Service Handbook page 89

(10) 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.
• TH2 or LPS of heat source unit.
• HPS of heat source 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.
OK?
Yes
HPS PS1 PS3
( p r e s s u r e c a l c u l a t e d
value) (The difference is
less than 0.098MPa)
OK?
Yes
No board or pressure
sensor abnormality.
Check that refrigerant piping and
transmission line connections are
in agreement between heat
source 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 heat source
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 the faulty connec-
tor on applicable pressure
sensor.
OK?
Yes
Remove the pressure sensor
connector from the board, and
check the pressure.
No
Pressure
range within 0 to
0.098MPa
Short connectors 2 and 3 on the
board and check the pressure.
Pressure
of at least 3.14MPa
indicated?
Yes
Replace the wrong pure-
ssure sensor by the cor-
rect pressure sensor, and
confirm detected pressure
is indicated correctly.
OK?
Yes
Change pres-
sure sensor.
–88–
Note 3
No
Note 4 Repair faulty connection.
No
No
No
Change board.