Mitsubishi Electric PURY-HP72 Service Handbook page 289

[8-9 Troubleshooting Problems with Major Components on BC Controller ]
1) BC controller: Phenomena when the pressure sensor is connected wrongly (reverse connection of P1 and P3) to the board.
Cooling-only
Normal Non-cooling
2) Check the self-diagnosis switch (Outdoor control board SW4 (SW6-10:OFF)).
Measurement data Symbol
Outdoor high pressure
Outdoor low pressure
BC controller pressure
(liquid side)
BC controller pressure
(intermediate part)
For how to read the SW settings, refer to the following page(s). [9-1-1 How to Read the LED](page 325)
3) Check whether CNP1 (liquid side) connector on the BC controller control board and the connector CNP2 (intermediate part)
are not disconnected or not loose.
4) Check the pressure value on the self-diagnosis switch (same as note 2) with the connector of the applied pressure sensor is
disconnected from the board.
HWE13080
Cooling-main
Indoor heating SC small
SC11 large
Heating indoor Thermo ON
SC16 small
Especially noise is large.
PHM large
SW4 setting value
1 2 3 4 5 6 7 8 9 10
ON
63HS1
1 2 3 4 5 6 7 8 9 10
ON
63LS
1 2 3 4 5 6 7 8 9 10
ON
PS1
1 2 3 4 5 6 7 8 9 10
ON
PS3
Symptoms
Heating only
SC11 large
SC16 small
PHM large
- 278 -
Heating main
Non-cooling
SC11 large
Indoor heating SC small
SC16 small
Heating indoor Thermo ON
PHM large
Especially noise is large.
GB