Removing freon from a vehicle without a recovery machine is not recommended, as it is a highly regulated and potentially dangerous process. Special tools are required to properly and safely removeFreon from a vehicle. This is because you not only have to worry about releasing the Freon into the atmosphere, but also managing the high pressure and temperatures associated with it.
The first step to removing Freon without a recovery machine is to locate your vehicle's low-side service port, which can usually be found on the passenger side of the vehicles AC system. You will then attach the Freon can tap valve to the service port, paying attention to make sure it is securely connected.
Next, you will carefully open the Freon canister's valve and allow the Freon to spray out of the can into the service port, making sure not to tilt the canister, so as not to release too much pressure all at once. Pay attention to the canisters temperature, and once it is cold it is usually safe to tilt the can slightly in order to access the remaining Freon, then close the valve and remove the canister.
Installing the new Freon is the same process in reverse, using a new canister and connecting the valve to the service port, opening the valve and releasing the Freon into the system, then closing the valve and removing the canister.
It is important to note that Freon must be handled in accordance with Environmental Protection Agency rules and regulations, and it is often best to enlist the help of a professional AC technician to help ensure the process is done safely and properly.