I put a new ac in my house and the house is still hot but thermostat is reading the temperature right and turns on and off very fast so the house doesn't cool down

What kind of t-stst do you have? Are you sure the temp output on the stat is right? And what sf of you house and tonnage of your ac unit?

1200ft house and no I have not checked the thermatas, I have a3 ton unit

Anouther thing to check is if your t-stat is close to a air vent

what kind of t-stst do you have? are you sure the temp output on the stat is right? and what sf of you house and tonnage of your ac unit?

1200sf I have a3 ton unit, no I have not did ant test on the thrematac

anouther thing to check is if your t-stat is close to a air vent

Yes there are three vents that are close by

This could be blowing cold air on the stat making it read wrong block off the closest one to the stat and try it.