Working air conditioning is wonderful in hot weather, and it can be frustrating when your house does not seem to cool down as much as you think it should. Even turning the thermostat down to a really cold temperature sometimes seems not to help. However, while your air conditioning could always be in need of repair, there are times when it's working perfectly fine even though it seems like it's not cooling much.
After the summer heat is over—as in, the day or so after the first cold front blows through—you might think that it would be easier for your air conditioner to cool down your house. The temperatures outside aren't so bad, so inside shouldn't be so bad either, right? However, you might find that your house remains really warm, with your air conditioner seeming to struggle to cool things down quickly.
That's not because your air conditioner has broken; it's because your house's walls have absorbed so much heat over the past few weeks and months that the heat still radiates into all the rooms even though it's cooler outside. The result is that your house seems warmer, and your air conditioner seems to be taking longer to work than you subjectively think it should. Give it a few days; by then, a lot of that absorbed heat will be gone, and you should notice your house getting cooler a lot faster.
On a really hot day, a super-hot heatwave day, walking into an air-conditioned room feels wonderful. However, it doesn't feel so wonderful when you've been in the room a while and realize you're still feeling hot. However, that doesn't mean the air conditioner has stopped working that well. Whenever you are in a situation where there's an air conditioner and a lot of heat, the cool air is going to have only so much of an effect. In other words, if the hot air is too hot, that's going to make the streams of cool air feel not so cool because the amount of cool air is just too small to fight against all the hot air.
Put your hand up near a vent and see if the air right there feels cold. Not cool, cold. If it does, the system is fine, and all that's happening is that the cool air is being overwhelmed by the heat radiating into the house.
Someone Left a Window Open
Today's houses have many, many rooms and windows, and there's a good chance someone left one of those windows open if your air conditioner seems to be struggling. Check all of the windows and external doors, too (also any doors leading into and out of the garage, which usually doesn't have air conditioning hooked up to it and which can get quite hot).
Of course, if you close all the windows and wait the few days for cooler weather to help your house cool down, and you're still having problems, then you should call an air-conditioning repair company for help. Don't wait too long; many problems are easier to fix when they're new.