Have you replaced your AC air filter recently?
A client recently commented about their AC not being able to cool their home. They stated it was blowing cool air, but not cold air.
Removal of the cover plate revealed that their AC evaporator coil was covered in ice and air was no longer able to flow through the coils to get cold. Picture 1 shows the ice build up on the refrigerant coils, and picture 2 shows the under-side of the coils, completely iced over on one side.
The root cause: insufficient air flow across the coil caused by a clogged air filter. When warm house air can not blow across the coil, the coil gets too cold, and the condensation freezes on the coil instead of dripping off.
Luckily, this was an easy fix - the unit was shut down to allow the ice to melt, and a new air filter was installed before restarting the unit.
Be sure to regularly change out your unit's air filter to keep your AC unit running!