My thermostat is set to 76 and it will not go down it has been at 85 for about 2hrs. The air coming out of the vents is cool and I changed the filter whay can it be?.

Possible= 1.low on refrigerant
2. dirty A-coil
3. dirty condenser unit
4. all of above

And this is only if you have checked and are sure all equipment is working properly

Possible= 1.low on refrigerant
2. dirty A-coil
3. dirty condenser unit