Hi. I have an unusual problem. Most of the time my bedroom is cooled just firn. However, in the late afternoon, when the sun is directly beating down on that room, the air conditioner, even though it is working, does not cool the room - the heat shoots up, the room gets humid, and the air even smells stuffy. After the sun goes down the room cools off again. Help, what

You probably do not have a large enough supply duct to the room. Under normal circumstances the room will cool but when a load is imposed as in the bright sun of the day it just does not have enough A/C out of the supply to overcome the heat.

Contact a HVAC company and see if they can increase the duct size.
Also have them look over your system for other hidden problems.

Hi. I have an unusual problem. Most of the time my bedroom is cooled just firn. However, in the late afternoon, when the sun is directly beating down on that room, the air conditioner, even though it is working, does not cool the room - the heat shoots up, the room gets humid, and the air even smells stuffy. After the sun goes down the room cools off again. Help, what
I have the same problem. Is it an upstairs room? Mine is, and as you know, heat rises. The room may be poorly insulated, like mine, and just can't hold the cold air.

Make sure the air filters are clean and the condenser coil on the A/C is clean. If the condenser coil is dirty the A/C will not keep up in the heat of the day.