When the weather is hot, ice may sound like a good idea… but not when it concerns your air conditioner.
If you see ice or frost on your refrigerant lines or your outdoor unit, you should take action. This build-up means the coil in the metal box, called a plenum, above or below your furnace is already iced over.
That ice is working its way down the lines to the outdoor unit. To perform a repair, the ice needs to be melted and the unit should be turned off.
Airflow restriction is a common cause of icing. So, check your filters to be sure they are not clogged. Also, be sure all registers are open and exposed.
Sometimes the air conditioner will run, ice up, then thaw when it cools in the evening and then ice up again during the day. A sign of this is water under the furnace.
Another cause of icing is a low refrigerant level, which means there is a leak somewhere and a service repair call is needed. Sometimes a leak can be found and sometimes not, which can be discussed with a service technician.