93 country A/C problems

I have searched and search for my problem but can not find anything. I just bought a 93 country and the ac is not working blows warm. The compressor kicks on and stays on and does not cycle on and off like a normal compressor it just runs till you shut the ac off via the switch in the car. So my question is if the compressor is kicking on it obviously has pressure which means it still has some r12 in it correct? I was told something has to be messed up because it should cycle on and off not just run. What is causing this? Does it just need more freon? or is there something else i should check. Its pretty miserable when it is 98* and you have two kids in the back. Will just adding some freon (thinking of using stuff called feeze 12? or i have access to a couple cans of r12) make it all work normal? Just trying to figure out why it isnt cycling and why if it is on its not even a little cold?? Thanks for the help

Since you just bought it, could be the prior owner defeated the cycling switch in an effort to make it work. I would put gauges on it to check the pressures. Keep in mind if it is low on refrigerant it's also probably low on oil.