Blower shuts off but heat coil does not.

How can you tell if your low on freeon or if the coils leak it freezes up

My ac keeps freezing up how do you know if you need new coils or freeon or what it freezes on the condenser coils and on the outside copper part.

When your low on freon then the indoor coil will feeze and you have a leak and that could be in the evaporator coil or the condenser coil or other parts as well.

The indoor coil can freeze for a number of different reasons:
1. Dirty air filter
2. Dirty indoor coil
3. Blower motor failure
4. Blower fan squirrel cage dirty
5. Low on refrigerant

These are just some of the possible causes. If there is a leak, it can usually be found near the indoor coil or in the outdoor unit. Depending on age, there are capillary tubes that can rub, causing a leak, schrader valve stems that leak, rust on an accumulator or the bottom of the compressor, terminals on the compressor, damage to the outdoor coil such as lawn mower hitting the coils. There are exceptions where a leak may appear somewhere in the lines between the indoor and outdoor units. These are rare, but possible. If the unit has had any work done to it, there are possible problems such as bad solder/brazing joints, sight glass leaks, safety device flare nuts leaking and even diaphragms on fan controls where the element attaches to the back or bottom of the control. Hope all of this helps.

One other thing concerning indoor coil freeze-ups... Check to be sure all return air grilles are clean and clear of obstruction and make sure that all supply air vents are open. It is a myth that closing vents in unused rooms helps cool other areas. While air velocity may increase to those spaces, the overall airflow across the evaporator (CFMs) is reduced. The unit is designed with a specific CFM requirement and closing supply vents or blocking return vents can cause a reduction in CFMs across the evaporator. At best, your efficiency is reduced and at worst, you can cause frosting, water leaks around the unit and eventual icing of the indoor coil.