How much Freon does my truck need?

Most vehicles need 25 to 35 pounds per square inch of Freon on the low side if the vehicle is running with the air conditioner on its coldest setting and fastest fan speed. The amount of Freon a vehicle uses is measured in pounds per square inch, or psi.

In some vehicles, such as Chryslers, a normal low-side reading may reach 15 to 25 pounds per square inch. The pressure on the high side should be 200 to 350 pounds per square inch. When the air conditioning system is off, the pressure equalizes on the high and low sides. In this case, the pressure of both sides should be 80 to 105 pounds per square inch.