Air conditioner intermittently (sp?) blows hot air when I am driving. Not consistant with acceleration or turns and just had the freon drained and recharged.

recharge the system

It may still be low on freon. It can hold several cans.
High side should be around 250psi and low around 35 or 45psi at idle if system is charged.
If you raise engine speed the low can drop below 20psi and switch off the compressor if the system is low on freon.
Could be a restriction in the system, bad relay, or bad a/c compressor-clutch.

car air conditioner blowing hot air is cause by either a leak or a clogged condenser, since it has a freon in it then it might be a case of clogged condenser but this is just a contributing factor, it is possible that the leak is small that you wont even notice that the freon is not enough for the a/c to blow cold air.

I have a feeling that no one is checking the blend door in the plenum.

You need to check your freon level. Go to your auto parts store and pick up a can of freon with a gauge and follow the directions on the can.

Most likely your problem is the same as mine, which means you have a crack in your air compressor therefore no matter how full you fill the freon it will always drain (or blow) right out. Solution - get a new air compressor. Try to find one in a chop shop junk yard type place if you can do it yourself.

Alternate problem - freon can lose its charge. You can take it to just about any auto store and get the freon charged up for about $70. If that doesn't fix the problem it is likely the compressor.

If putting freon in made the a/c stay cold for 4 days then you need to have the system checked for a leak

plse switec off 2hours

If the fans are working that means the a/c system is operational. Try letting a little freon out while the a/c is on and see if the pump stays runnig. If so Shut the a/c off, drain the freon and replace with r134a and enjoy

Take it to a garage and have them evacuate the system and refill with refrigerant. you have air and non condensibles in the refrigerant system.