Air conditioner icing up

[Snowandsail]

Anyone know what this indicates? Air conditioner is icing up

[S/V Illusion]

Don’t see ice but the two common causes are low refrigerant or poor ventilation

[sailorboy1]

Air flow issue

[SailingHarmonie]

Low refrigerant.

If the internal pressures are correct, it should not ice up even with very limited air flow. The internal pressures are a function of the amount of refrigerant in the system.

This is ABSOLUTELY the case when it ices from the bottom up as your picture indicates is happening.

[GordMay]

If there isn’t enough warm air blowing through the evaporator coil, to transfer the heat, the refrigerant will not turn to warm gas. Instead, the refrigerant freezes – in the evaporator coil, or in the line.
Poor air flow is the most common, and most easily remedied, root of the freeze-up problem; but there are several reasons why that might happen.

In no particular order:
1. Clogged Air Filters.
2. Blocked [or closed] Supply and Return Air Vents [or ducts].
3. Faulty Blower Fan, or fan speed set too low.
4. Clogged Condensate Lines - If the drain line is blocked, water becomes trapped near the evaporator coil, and freezes.
5. Dirty Evapourator Coil.
6. Air Conditioner Is Oversized for the space it serves [short cycling]. Run AC on Fan Only [to defrost], then Set thermostat to Higher Temperature.

Low Refrigerant Level - this is NOT a DIY job, for the average boatowner.

[Mr. Kevin]

Wow, I was looking for ice, not hoarfrost. Pretty sure it's air flow and humidity. Water condensates out of the air into a cold surface them freezes in place. Could you insulate the pipes so that they are not as outwardly cold?

[Snowandsail]

Thanks for all the advice. This ac unit has been running in the same conditions for 5 months with no issues. Since this is a new issue and the airflow hasn’t changed and the filter is clear and the sea water pump is pushing water through the system, I think the most likely issue is low refrigerant.