How to Change Air Conditioner Freon

While changing the Freon in an air conditioner is not an easy task, you can do it yourself without seeking the help of a technician by following some simple steps.

Freon is a pressurized refrigerant, which is used as a coolant in air-conditioners. It helps to maintain the temperature, which is necessary for the smooth functioning of the unit. You may assume that any decrease in the air conditioners’ performance is associated with the lack of Freon. 

However, this is not necessarily the case. The problem is generally related to the maintenance aspect of the system. Check the refrigerant charge if the machine fails to function efficiently even after performing the basic cleaning steps.

Points to Consider before Beginning with the Procedure

  • Refrigerants do not need periodic charging.
  • Recharge Freon or change Freon if there is a leakage in the system.
  • Change the refrigerant if you are assembling a system or changing a part of the unit.
  • Avoid overcharging or undercharging the unit with refrigerants.
  • Use warm water to heat up the refrigerant cylinders.
  • Trap the excess refrigerant in a recovery cylinder.
  • Do not allow the refrigerant to escape into the atmosphere.

Many people end up recharging the refrigerant even when not required.

  • Recharging is a must when you observe bubbles inside the unit
  • The refrigerant is sufficient if the amount of refrigerant superheat and sub cooling is about 10 degreesF.

    How to Recharge Air Conditioner from the High Pressure Side

    This technique should be used for capillary tube fitted systems and in the case of insufficient sub cooling. Follow these steps to recharge the Freon in the air conditioning unit:

    Step 1: Stop the compressor and check the refrigerant in the system

    Step 2: Purchase the required refrigerant and connect the refrigerant cylinder to center manifold’s hose of the pressure gauge set.

    Step 3: Connect the pressure gauge’s hose to the service valve of the unit

    Step 4: Take out the protective cover of the valve before connecting the pressure tube

    Step 5: Throttle the regulator of the refrigerant cylinder

    Step 6: Close the cylinder’s regulator and operate the air conditioning unit. Check the sub cooling and ensure the water gauge or sight glass is clear

    How to Recharge Air Conditioner from the Low Pressure Side

    This technique is recommended when the superheat is insufficient and is used for valve fitted systems. Follow these steps to recharge the Freon in the air conditioning unit:

    Step 1: Stop the compressor and check the refrigerant in the system and purchase accordingly.

    Step 2: Connect the refrigerant cylinder to the centre hose or tube of the pressure gauge system.

    Clean the entire line by throttling the regulator.


    Step 3:     Connect the gauge tube or hose to the service valve.

    Step 4: Open the gauge’s regulator and throttle the cylinder’s regulator to regulate the flow.

    Step 5: Close the regulator of the cylinder and activate the air conditioning unit.

    The same procedure can be done by using a weighing scale to measure the weight of the refrigerant cylinder. Close the regulator of the cylinder when the appropriate amount of refrigerant is added to the unit.