Ice in Central Air Conditioning

Air Conditioning Condenser UnitIt’s a hot, muggy day, and your central a/c doesn’t seem to be helping as much as it used to, if at all. The air flow seems to be less than ideal, and what is flowing isn’t cooling things down much. You go down to the basement and check the air filter to see if it’s clogged, but it looks fine. So you go outside to have a look at the condenser box. Everything looks ok, until you see a big block of ice covering the junction where the pipes lead to the house. Not good. All you can think of is how can I fix that without calling a repairman?

In a word- don’t. There are many reasons for icing air conditioner coils, the most common of which is low refrigerant level. It is illegal in the U.S. for any person not certified by the EPA to handle refrigerants. Central air systems work by circulating refrigerants- chlorofluorocarbon, freon, hydrochlorofluorocarbon- in a sealed circuit. Procedures for properly charging the refrigerant in your system, what the correct pressurization should be, fixing leaks, and disposal of any waste refrigerant, all need to be done by that repairman you didn’t want to call. This is not a DIY project.


The ice can be caused by a number of things, but the most common cause is a deficiency of refrigerant in the system due to one or more chronic leaks. The ice you see forms on the coils form when the system is low on charge because part of the coil then runs very cold relative to the rest of it and ice starts to build. The ice will continue to grow, since it acts as insulation, more and more, until the coil and refrigerant lines are one big block of ice.

Other causes could also do this, like an airflow blockage due to obstructed air ducts, dirty air filter, or a dirty evaporator coil. Also, your ac/c system might have the improperly size evaporator coil or compressor for the size of the system. A bad fan motor or clogged coil could also be at fault. Only a qualified technician will know for sure.

So now all you can think about is how much is this going to cost?

Bottom Line

Well, it depends. With so many possible causes, it will vary. The minimum will be whatever the technician charges for a house call, but it could be a simple fix, or a complicated one. In the case of a simple fix, it might be $100 for topping off the Freon charge plus a new Schrader valve. On the other end of the scale, your refrigerant lines might need replacing, along with new valve fittings, a complete repair could run you three or four hundred dollars.

Worst case, you could wind up with a bill of $700 and up, if there are multiple problems happening, and that cost could well be more in a large city or desert areas. Either way, you need to call a service tech and have him evaluate the problem, only he can know for sure what is wrong and how to fix it.

Further Help

The following organizations are some of the many that have more information and can help you in finding a reputable professional to service your air conditioning in your area.

Air Conditioning and Refrigeration Institute (ARI)
4301 N. Fairfax Drive, Suite 425
Arlington, VA 22203
(703) 524-8800
Fax: (703) 528-3816

ARI represents manufacturers of air conditioning, refrigeration, and heating equipment and has consumer brochures on a variety of topics.

American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)
1791 Tullie Circle, N.E.
Atlanta, GA 30329
(404) 636-8400
Fax: (404) 321-5478

ASHRAE is organized solely for the purpose of advancing the arts and science of heating, ventilation, air conditioning, and refrigeration for the public's benefit through research, standards writing, continuing education, and publications.

Air Conditioning Contractors of America (ACCA)
1513 16th Street NW
Washington, DC 20036
(202) 483-9370
Fax: (202) 234-4721

The Air Conditioning Contractors of America is the most active and widely recognized organization representing contractors in the heating, ventilation, air conditioning, and refrigeration (HVACR) industry.