Check the caulking around the PTAC wall sleeve to make sure all air and water openings are properly sealed.
Check the wall sleeve's level. It should be tilted to the outside (as close to 1/4 bubble tilt as possible); however, do not over- or undertilt. If the unit has an internal drain system, the sleeve should be leveled (left to right and front to back) so that condensate water drains into the connected drain line/kit location. Water should not overflow the sleeve to the room side or outside and should drain into the internal drain hole. (To test, pour a cup of water into the wall sleeve.)
Allow unit to dry for 24 hours before reapplying power. When power is reapplied, test the unit for proper operation.
Check clearance around the PTAC unit to ensure that the intake air and discharge air paths are not blocked or restricted. Leave a minimum of eight inches between the intake vent and furniture, beds, or other objects for proper operation. Make sure no objects (curtains, furniture, etc.) block the discharge vent.