Neptune MAH5500AWW make noise like metal rattling

if the catch on the door is ok then you need a new door lock assembly.

Mine is doing it. What was your final result?

Check for a cold water supply problem, since cold water is what is used in the rinse. Check the water inlet valve. Remove the water supply hoses and check the small metal screens inside the openings on the valve. Make sure they are clear of rust or debris (especially the cold water side) and check the solenoids. They can be tested using a multimeter or ohmmeter. Check for continuity. A lack of continuity means a bad solenoid. I will attach a photo for reference. Hope this helped and best wishes.

If it does not make the noise when the fan is ruunin you may ahve abroken sping in the compressor. Make sure you Window unit is level. If not the compressor will knock on the inside. Rusty

if the water continues to fill even with power off, and you have to manually shut in off at the wall valve, the 3-way inlet valve is stuck open. you have to replace it. $90

The balance sensor is likely failed.

Check the shock absorbers and springs for breakage.

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cold water valve screen plugged or bad valve, just check it!

Are you getting cold water to fill ?How is the water pressure?Timer maybe at fault here.

Check latch mechanism for alignment. Often operation of machine loosens latch mechanism causing internal switch for "door open (or ajar)" preventing rinse or spin cycle. Opening and closing door presses latch mechanism closing internal switch allowing for continue processing to rinse or spin cycles.