technician charging an air conditioner with refrigerant

How to Tell If Your AC Needs Refrigerant

The refrigerant in your central air conditioning system plays a key role in the cooling process. It absorbs heat from your indoor air and circulates outdoors so that the heat it absorbs can be released. Without adequate refrigerant, your air conditioner won’t function properly.


Air conditioners typically have refrigerant problems for one of two reasons:

  • A leak formed, and your system is losing refrigerant. In this instance, the leak must be repaired, and then your AC must be “recharged” with new refrigerant.
  • Your air conditioner‘s refrigerant was not properly charged when the air conditioner was installed.

Keep in mind: air conditioners do not use up refrigerant. The refrigerant travels in a closed loop, changing from liquid to gas and back again. Beware of technicians who tell you the problem can be solved by “topping off” the refrigerant and who want to charge you for “refills.”


Air conditioners that do not have enough refrigerant typically display the following signs.

Ice forms on the evaporator coil.

The evaporator coil is located inside your indoor AC unit. When everything is working correctly, refrigerant flows through the evaporator coil, and there it absorbs the heat from your indoor air.

When there isn’t enough refrigerant, this creates a pressure imbalance that can cause the refrigerant to “overcompensate.” As a result, condensation that collects on the evaporator coil freezes and starts to form layers of ice. Ice can also form due to problems like lack of airflow, so make sure that you have a clean air filter in place!

Ice forms on the refrigerant line.

Sometimes you can see a layer of ice forming around one of the lines connected to your outdoor AC unit. This is a sure sign of a refrigerant leak.

The refrigerant line makes a hissing or bubbling sound.

This is the sound that a refrigerant leak can make. You’ll only be able to hear it while your air conditioner is running.

Warm or lukewarm air blows out of your vents.

A lack of refrigerant will make it harder for your air conditioner to cool the hot air moving through it. As a result, the air coming back into your home won’t feel as cold as it should.

HVAC refrigerant repairs require professional equipment and training. If you suspect your system has a refrigerant-related issue, don’t hesitate to contact our courteous Arlington technicians at Tom's Mechanical, Inc.: (972) 388-3669.