602NT

Inspect refrigerant circuit: check R410A charge level and operating pressures (high-side and low-side) against manufacturer specifications; verify for leaks at fittings, valve caps, and compressor connections

Inspect and clean sea-water (raw-water) heat exchanger: check cupro-nickel or titanium tubes for biofouling, scaling, or corrosion; verify water-side pressure drop and flow rate against spec (e.g. 2.2–3.3 m3/h for CU70VFD)

Inspect BLDC inverter drive and electrical connections: check DC bus voltage, inverter output waveform, tighten all power terminals, verify startup current does not exceed 2 A limit, check for fault codes on touch-screen display

Inspect freshwater (chilled-water) circuit: check pump operation, glycol concentration, expansion vessel pre-charge pressure, and all flexible hose connections for leaks or chafing

Inspect compressor operation: verify no abnormal noise or vibration, check oil level if sight glass present, confirm speed modulation across 20–100 Hz range under varying load

Inspect safety sensors and controls: test high-pressure switch, low-pressure switch, and water-flow safety switch (all 4 sensors on NT/604 series); verify temperature sensor accuracy at chilled-water supply and return

Inspect thermal insulation on cold surfaces and chilled-water piping: check for condensation, moisture ingress, or insulation delamination that could reduce efficiency or cause corrosion

Inspect sea-water strainer and inlet/outlet seacocks: clean basket strainer, check seacock operation and seating, inspect anti-corrosion zinc anodes on sea-water circuit fittings