MRCOOL ductless-mini-split — MRCOOL DIY mini-split generations that report an inverter compressor drive fault Error Codes Directory

MRCOOL P4 and PC-04 error code: inverter compressor drive fault

MRCOOL uses this code for an inverter compressor drive fault, shown as P4 on generations before the fourth and as PC-04 on fourth generation DIY equipment. The drive electronics that run the compressor have reported an abnormal condition and stopped it. The cause differs between a newly installed system and one that has been running. Applies to: MRCOOL DIY mini-split generations that report an inverter compressor drive fault This meaning follows MRCOOL DIY support literature for the generations that display P4 or PC-04. The generation matters more than the digits, because MRCOOL renumbers codes between series, so identify the DIY generation from the model number before using this page. Owner-safe checks: Identify the DIY generation from the model number so the correct code table and parts list are used. | Isolate power at the breaker for fifteen minutes, then restart once, and note whether P4 or PC-04 returns. Qualified technician: Testing the run capacitor, contactor, inverter module, and compressor current, and checking supply voltage under load, require a qualified technician working at energised terminals.