Air conditioner is not cold; everytime I turn it on, it blows hot air. I think it needs freeon. how do I re-fill it?

Assuming you have R134a, you can purchase a can or two of refrigerant most anywhere... Parts stores, Walmart, most anywhere...

There is only one nozzle this fits. It is sticking up off a large diameter pipe coming from your air conditioning compressor (on the engine) going to the accumulator (drier) located near the back corner at the firewall

If your in doubt, you can always pull into a local shop and simply ask them to point it out for you. There are refrigerants which come from a filling tube which has a PSI guage on it, so that you can easily fill it to the proper level that you need.

If the nearest Napa, Shucks, oreilys or Autozone is too far away, Just go browse the automotive section of your local store, Walmart, Kmart even Walgreens and Rite Aids have these. an 18 oz can is about 18 dollars with the guage

Hope you find this helpful

Good Luck and Happy Motoring

Respectfully