We have an A54 with a 230v 160 LPH Dessalator, water cooled air conditioning, and a Volvo 110 HP engine. 

1) When operating the Onan, water maker, and the Volvo above approximately 1250 RPM the low-pressure gauge on the water maker drops from 20 psi to negative 10” hg, the high-pressure pump starves, and the water maker shuts down.

2) When operating the Onan & water maker everything operates correctly IF the air-conditioning is started first.  If the water maker is started before the air conditioner when the water maker is started the low-pressure pump pressure drops and the water maker shuts down due to low-output pressure on the high-pressure pump.

All tests were run with a clean sea strainer and a clean raw water intake pipe, it was scrubbed with a round brush that reaches through the hull.

What has been your experience?  Any thoughts?  Thanks in advance.

Mark & Debbie Mueller

A54 – 68

Brass Ring

Ft. Lauderdale