Genuine Daikin 346403 Compressor is the sealed compressor that circulates refrigerant through the outdoor unit, generating the pressure difference the cooling and heating cycle depends on. When it fails the unit loses compression and stops producing cooling or heating, typically stalling and tripping on overload. Its run capacitor and contactor rarely come through a compressor failure unscathed, so they are worth renewing in the same visit — and sourcing the compressor genuine through our authorised Daikin channel means the replacement matches the original by specification, not by closest-available guess.