What Is the Procedure Before Checking the Refrigerant Charge?

Check for Symptoms

• Look for symptoms in your cooling system that would indicate the possible need for more refrigerant. In an air conditioner, you may find that the evaporator coil is icing up because of low levels of refrigerant. You may also notice that the air blowing out of your registers is not as cool as it should be. For a refrigerator or other cold storage appliance, you might notice food thawing in the freezer compartment or a lack of cooling in general.

Check for Leaks

• Contact a refrigeration service technician that specializes in handling and recharging refrigerant. They will have the proper tools to check for leaks in your system. An electronic leak detection device used by these professionals can find even the smallest leak that results in a 1/2-oz of refrigerant loss per year. If there is a leak, then the refrigerant should be recovered without allowing it to release into the atmosphere. Then, the leak will need to be repaired prior to recharging.

Gather Tools

• Checking the refrigerant level in your air conditioning or refrigeration system requires a special set of tools. The standard equipment used in testing the charge level of refrigerant is a set of gauges and a manifold. These tools hook into the refrigerant fill lines and indicate the amount of pressure in the low and high pressure sides of the system. This readout will tell you how much refrigerant is in the system. You must use the correct set of gauges for your particular type of refrigerant since they each require specific gauge readings.

Measure Airflow

• Before you can get an accurate reading of the refrigerant charge in your system, particularly with HVAC systems, you will need to measure the airflow across the evaporator coil. This is typically done by calculating the velocity of the airflow multiplied by the area of the registers. The figures are usually stated in cubic feet per minute per ton, or CFM/T. The ideal airflow measurement should be between 350 and 450 CFM/T.