Why Does My Air Conditioner Freeze Up?

May 7, 2015

Don’t let frozen evaporator coils ruin your summer!

Picture this: you just returned from a long run outside, only to find that your air conditioner is broken! The cause of your AC troubles? Frozen evaporator coils. But, how do you know what causes your air conditioner’s evaporator coils to freeze up, causing your entire air conditioner to stop working?

What Are Evaporator Coils?

There are several reasons why your air conditioner is frozen and no longer working – one of which is frozen evaporator coils. The evaporator coils are located in the indoor unit of your air conditioning system. When your air handler blows return air over the coils, the refrigerant inside the coils absorb heat and cause the temperature of the return air to drop. When this occurs, the cool air (which is now the supply air), is forced back into your home.

What Causes My AC to Freeze?

Improper air flow – When air flow is limited in your air conditioning system, it can cause your coils to freeze and your entire air conditioner to stop working. Check to make sure no boxes or materials are blocking the return vent. This vent is where warm air returns to the indoor portion of your cooling system. If air flow is blocked, chances are your evaporator coils will freeze over.

Solution – Remove any equipment blocking the return vent, causing your air conditioner to freeze up.

Broken thermostat – When your thermostat is broken or not set properly, it may cause your air conditioner to run for long periods of time without cycling off once its desired temperature is reached. In fact, it could cause your air conditioning system to not turn off at all and result in a frozen air conditioner.

Solution – First, check to make sure that your thermostat is set to your desired settings, then test the thermostat to make sure it is functioning properly. If it is not, or your thermostat does not turn on, you can try replacing its batteries. If that still does not work, call a heating and cooling contractor to assist you.

Low refrigerant levels – If your air conditioner is frozen, you may have a refrigerant leak in your coils or somewhere else inside your unit. When this occurs, refrigerant slowly leaks from your air conditioner and causes your evaporator coils to freeze up.

Solution – Call an HVAC professional to inspect and repair any refrigerant leaks.

Dirty evaporator coils – If you don’t schedule an annual air conditioner inspection and tune-up, dirt and debris can coat your air conditioner’s evaporator coils. This makes it more difficult for your coils to absorb heat and result in a frozen air conditioner.

Solution – Contact a local HVAC contractor to schedule AC repair. Additionally, be sure to schedule an annual system tune-up to prevent from future breakdowns and increase the efficiency of your cooling system.

Broken evaporator fan – Your air conditioner’s evaporator fan works to pull warm air across the evaporator coils. When the evaporator fan is not functioning properly it causes your air conditioner to freeze, creating an uncomfortable home for family, friends, pets, and guests!

Solution – Unfortunately, a broken evaporator fan is not a DIY-type fix. Repairing or replacing a fan requires the expertise of a professional HVAC contractor.

Air Conditioner Repair in the Cincinnati, OH Region

Rick’s Heating & Cooling is a family-owned and operated heating and cooling contractor servicing Cincinnati, OH and its surrounding southwestern Ohio communities. We service Warren County, Butler County, Hamilton County, Clermont County, and Clinton County.

If you notice your air conditioner is freezing up, be sure to give us a call at 513-899-6005! We can diagnose and repair your AC unit and restore the comfort to your home. Contact us today to schedule service!