Charging a Ford F-350's air conditioning requires the same process used in other vehicles. However, before attempting to recharge the system, you will need to know which type of refirgerant your F-350 uses. Your truck will take either R12 or R134a Freon, and which it is depends on the Ford's year of manufacture. R12 is not eco-friendly and it is only used in older F-350s. If your truck post-dates 1984, then you will likely be using R134a. Double check your owner's manual before buying a recharging kit.
Locate your F-350's air conditioning pipes within the engine. They are aluminum, and will feature two pressurized connection ports. The high side port is irrelevant to this task; it will not even fit your recharging kit's port. Uncap the low side pressurized connection port and connect your recharging kit's service hose.
Place the recharging kit in a safe resting spot. It needs to stay away from belts, fans, or anything that will move once you crank the F-350's engine. Leave the engine and take a seat behind the truck's steering wheel.
Start the Ford's engine. Wait for the engine to fully warm. Then, switch the Ford's air conditioner on. Set the blowing force on high, and use the coldest air setting. This will permit you to take accurate temperature readings within the air conditioner itself.
Exit the F-350's passenger compartment. Open all the doors as a way to ensure the air conditioner does not accidentally shut itself off.
Twist the nozzle atop the Freon recharging kit and open the canister. The freon will flow through the hose and into the Ford F-350's air conditioning pipes. This will make a loud and gassy "rush" sound.
Allow a minute to pass and then shut off the flow of Freon. This will help stabilize the air conditioning system, and the Freon will circulate and evenly distribute throughout the system. Let this happen by waiting at least a minute before adding more Freon. Monitor the kit's pressure readings while you wait.
Place a thermometer into the air conditioner's central duct. Take readings from this thermometer as you add further spurts of Freon into the system. Once the conditioner's internal air temperature reads 40 degrees, the system has been recharged.
Remove the thermometer from the duct. Remove the kit's service hose from the low side pressure port and replace the port's cover. Let the engine and the air conditioner run for ten minutes before shutting everything down. This will ensure an even distribution of Freon.
