This is probably a problem with your vehicle's A/C system being low on Freon. Freon is what your vehicle's A/C system to cool down your vehicle. It does this by transporting the hot air out of the cabin to the outside where it expels it cools itself again and then re enters the cabin. Without a Freon charge, which is lost over time and is normal, your A/C system will lose it's ability to cool the cabin down.
I have included a few links for you to go to down below.