After driving and turning car off and it's sat for a while the drivers side mat is wet,please where is the water coming from?1996 Toyota Cavalier car

Sun roof ¿
wiper motor compartment
full of leaves
rust issues
door seals?

It sounds like your heater core is done. That is in a tight spot in behind the glove box. Get a new one for around $60.00.

shop vac the carpet dry then spray garden hose around both rear doors or around doors and see if you get wet or see a leak. Also spray under vehicle on both sides of car and check for leak.

The water probably went down between the window and the door. On the bottom of the door is a drain hole, with all that rain it looks like the water in the door washed some dirt or something over the hole and stopped it up but not before it went inside the car and onto the carpet. Just unplug the hole with a small stick or something and watch for the water drain out. Open the doors and let your car dry out. Should be O.K.

I would say you have either a bad seal on the windshield or the seal on the passenger door opening.

Check the park brake position sensor switch.
The sensor switch or the parkbrake actuating lever position may be mal-adjusted.

If this has happened since you started using the A/C it is probably the drain tube for the A/C. They get plugged and usually someone has to go under the car with a coathanger and open the tube up.

Check with Toyota Parts. I'm sure there is one, but it is unavailable at a retail parts store. Heater cores are pretty much as necessary as the four tires on the outside are. My advice would be to remove the core and check the hose clamps or connections for other issues. You want to be sure that the leak is in the core and not in one of the hose connections. I think that is odd that your driver side floor is wet and not the passenger side. Open the hood and look for coolant hoses attached to the firewall (the sheet metal between your dash and the motor) and see if they are on the driver side or the passenger side.

There may be a clogg in the drain for your air condition. Or the drain for the water coming off of the windshield (on the bottom where the wiper blades are, may be clogged with leaves or debris. To check take a hose or alot of water and pour on windshield then look to see if it drips inside on the driver floor. To check if its an Ac drain leak turn AC on and run for a while and check to see if the mat is wet or water is dripping on floor mat. Good Luck

I believe the problem is a leak in your heater core. The water would run down the inside of the firewall or near it thus running under the mat.