Bc Controller Transformer - Mitsubishi Electric City Multi PQHY-P72 Service Handbook

[ IX Troubleshooting ]
Check whether the BC board output signal corresponds with the solenoid valve operation correspond.
Note1 SVA, SVB, SVC
SVA, SVB, and SVC turn on or off according to the indoor unit operation mode.
Port
SVM,SVM2
SVM1 and SVM2 turn on or off according to the operation mode.
Operation
Cooling only
mode
SVM1
SVM2
Note2 SVA, SVB, SVC
Measure the temperature at the upstream and downstream pipes
Measure the temperature at the upstream and downstream pipes

4. BC controller transformer

CNTR(1) - (3)
CN03(1) - (3)
*Before measuring the resistance, pull out the connector.
Cooling
SVA ON
SVB OFF
SVC ON
Cooling main
Pressure differ-
ON ential control
OFF or ON
OFF OFF
BC controller control board
CNTR
Red White
Normal
about 58 ohm.
about 16 ohm.
- 288 -
Mode
Heating Stopped
OFF OFF
ON OFF
OFF OFF
Heating only Heating main
OFF OFF
Pressure dif-
Pressure differ-
ferential con-
ential control
trol
OFF or ON
OFF or ON
and of SVA.
and of SVA.
CN03
Red Red
Abnormal
Open-phase or shorting
Fan
OFF
OFF
ON
Stopped
OFF
OFF