How do you diagnose high humidity problems with a Sun wall mounted air conditioning unit?

Question

I have checked my superheat and subcooling.All perameters appear to be proper. I have adjusted the fan settings to automatic,incase the humidity was from the drying of the evaporater.But still,after the unit shuts off the humidity levels in the room climb to 75% in just minutes. Any ideas?

Answer 1

You have to find the source of the humidity and eliminate it.

If the a/c unit is too large, it will cool the area fast and make it fell damp and clammy. An a/c unit that is way over sized only cools - does not properly remove the moisture form the air.

When you say you checked the superheat and subcooling, do you mean you checked the refrigerant pressures. If the refrigerant level is too low, the unit will cool faster and may cause the problem you stated. Check the evapourator for icing. If there is a greater buildup of ice than normal, chances the refrigerant is low.

The best design for an a/c unit is to have it slightly undersized. The unit will run longer and remove the moisture from the air thus reducing the humidity.

Sources of humidity:
Openings such as windows and doors
large sources of open water such as fountains,
swiming/wading/ornamental pools, large plantings of live
plants that must be kept moist.

How to eliminate:
Windows and doors:
Keep closed as much as possible. Have double
entrances for doors and /or a air curtain (special fan
placed above the door whch blows a high volume of air
straight down in front of the door creating an air barrier
prevent the outside air from mixxing with the inside air.
Sources of open water:
Partician them off from the main room by placing a glass
wall around them.

Answer 2

I may be that you simply have too large a unit or it is not hot enough to require the unit to run enough to pull down the humidity enough.