System: Mitsubishi MXZ-8C60NA2-U1 (5-head multi-zone outdoor condenser)
Symptom: Indoor units blinking 7 times
Working through this one now — will post the full diagnosis, photos, and fix once I’ve got more details tomorrow. Dropping this here as a placeholder in case anyone’s seen this exact symptom on an 8C60 setup and wants to chime in with what they’ve found.
Initial findings on site:
Checked one of the 5 indoor wall-mounted air handlers. The upper LED was flashing 7 times, which indicates “outdoor control trouble.”
Outdoor unit findings:
Next I went to the outdoor unit and removed the service access panel. The control board display read 4250 / 51. Note: the error code will display as a 4-digit code followed by the address number — 51 is always an outdoor address.
Compressor testing:
I then pulled up the outdoor service manual on MyLinkDrive.com. I turned the outdoor power disconnect to the off position. I confirmed wiring to the compressor was correct/fastened properly and continued to test the power/inverter by switching SW7-1 to the on position. I confirmed the power supply to the outdoor unit was turned off and continued to remove the U/V/W connectors from the compressor. I turned one of the indoor air handlers on to cool mode. The outdoor fan motors turned on and ran for a couple minutes before shutting down. After 3 on/off cycles, a 5300 error was displayed. I tested the windings on the compressor and found the windings to be shorted to ground.
Diagnosis: Shorted compressor windings. A new compressor is on its way and will be installed within a week or so.