A/C & Heat Help!
 

I bought a 97 civic lx a few months ago knowing it needed work. Honestly, I don't know anything about cars and don't have the money to pay anyone so, before I begin if you can help me PLEASE give as much detail as possible.
So here's the problem, when I turn the a/c heater switch on it doesn't blow on 1 or 2 but works on 3 and 4..someone told me this was the blower motor resistor, my passenger floor board stays wet..someone told me that was the heater core but I don't notice a smell besides my carpet just from being wet for so long and the heater works, my air conditioner somewhat worked when I bought the car and now it's not blowing cold anymore..I was told that's from needing freon, lastly like I said settings 3 and 4 blow but I don't think they're blowing as hard as they should.
I guess I possibly have the answer to what's wrong but I'm wondering if there's something else that maybe wasn't thought of when my friend was looking at my car? I don't know how long all this has been going on but I find it kinda odd it's all breaking/messing up around the same time and being 4 different problems. If you don't have any suggestions to what else it could be I still need help changing the heater core and resistor if you could tell me how to do that.
Thanks!

Take the blower motor out and check for a mouse nest in the ductwork. That is quite common and it will cause reduced air flow and also can burn out the resistor (it depends on air flow to stay cool). To replace the resistor, take the glove box out of the car (unscrew the hinges at the bottom, then pop the latch), then the resistor is right there mounted on top of the duct.

The water could be rain water coming in a hole in the car, or (while the A/C was working) water condensed from the A/C. Keep an eye on the coolant level in the radiator and see if it is going away. If the heater core is leaking, replacing it requires taking the whole dashboard out of the car. That is not as complicated as it sounds but it will take some time to do it carefully.

You'll need to find the leak in the A/C system. It sounds like there is a rather large leak and the seller just regassed it so it would work for long enough to get the car sold. The charge of refrigerant should last for years (theoretically forever, but nothing is perfectly airtight) if the system doesn't leak. The only reason that "freon" goes away is because it has leaked out. It is not "used up" i.e. consumed during normal operation. Do not use "stop leak"-- it very seldom works and will cause major damage, contaminating the system and making a proper repair impossible without replacing the entire system.