Subject: AOUH36KWAH4 & AOUH45KWAS5 Compressor Noise

Purpose: This bulletin provides information regarding an identified condition and the approved corrective action for the H-Series, R-32 Multi-Zone outdoor units, model number AOUH36KWAH4 & AOUH45KWAS5. This is a fix-on-fail correction and does not affect system performance

Discussion: During low load conditions when in the heating mode, the twin rotary compressor may exhibit an occasional noise, due to low compressor speed. The noise is not noted during increased heating load conditions or in the cooling mode.

Corrective action: A firmware update revision in the outdoor unit Main PCB provides a slight increase in the compressor minimum heating speed. This firmware adjustment eliminates the reported condition. The firmware update (outdoor unit Main PCB replacement) is recommended only for systems with a confirmed compressor noise report.

Parts Exchange Process: For systems that are operating and experiencing compressor noise, please open a service ticket in Zendesk and email [email protected]:

• (1) Main PCB with the updated firmware will be shipped directly to the contractor.

• A prepaid return label will be included for the return of the original PCB to the Quality Assurance Department in New Jersey.

 -The exchange process will be complete upon receipt of the original Main PCB by the Quality Assurance Team.

See attachment for full details