20 Nov 87

Symptom: MGTC-20, DXTC-20, DXTH-20 – ERROR CODE P9

Solution: MULTIPLE SOLUTIONS

Cause: COMPRESSOR DRIVING PROTECTION

Remarks:

DESCRIPTION:

WHEN THE COMPRESSORE IS STARTING UP OR IT IS IN THE PROCESS OF OPERATION, THE OUTDOOR UNIT WILL SHUT DOWN AND SHOW THE P9 PROTECTION CODE IF:

1. THE MCU CANNOT TEST THE FEEDBACK SIGNAL FROM COMPRESSOR, OR
2. AN ABNORMAL SIGNAL IS DETECTED FROM THE COMPRESSOR, OR
3. THE COMPRESSOR STARTUP IS ABNORMAL

REPAIR:

1) CHECK THE WIRING CONNECTION OF U/V/W. IS THE SEQUENCY AND/OR CONNECTION CORRECT?

2) IF THE AC UNIT IS TURNED OFF AND TURNED BACK ON AGAIN IN A VERY SHORT PERIOD OF TIME, THE P9 IS A NORMAL PROTECTION BECAUSE OF THE COOLING SYSTEM HIGH PRESSURE AND LOW PRESSURE BALANCE

3) IF THE AC UNIT DISPLAYS THE P9 PROTECTION CODE AFTER THE COMPRESSOR STARTUP, AND IT THEN STOPS WORKING, PLEASE REPLACE THE OUTDOOR UNIT PCB