Mitsubishi Electric PQHY-P200YLM-A Service Handbook page 371

[ IX Troubleshooting ]
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 (Heat source control board SW4 (SW6-10: OFF)).
Measurement data
Heat source high pressure
Heat source low pressure
BC controller pressure
(liquid side)
BC controller pressure
(intermediate part)
ON
1 2 3 4 5 6 7 8 9 10
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.
HWE15060
Cooling-main
SC11 large
SC16 small
PHM large
Symbol SW4 setting value
ON
63HS1
1 2 3 4 5 6 7 8
ON
63LS
1 2 3 4 5 6 7 8
ON
PS1
1 2 3 4 5 6 7 8
ON
PS3
1 2 3 4 5 6 7 8
The figure at left shows that the switches 1 through 5 are set to ON and 6 through 10 are set to OFF.
Symptoms
Heating only
Indoor heating SC small
SC11 large
Heating indoor Thermo ON
SC16 small
Especially noise is large.
PHM large
9 10
9 10
9 10
9 10
- 362 -
Heating main
Non-cooling
SC11 large
Indoor heating SC small
SC16 small
Heating indoor Thermo ON
PHM large
Especially noise is large.
GB