Water is coming out of the overflow of th a c if the car is of

Okay, if its Clean water under the car, It is supposed to do that. It does it while you drive too.
If it is leaking onto the floorboards inside the car, No, it is not supposed to do that. If this is the case....

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, it's been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!