Why your air conditioner is freezing up

Written by the team at Panda Heating and Cooling · licensed TDLR TACLA128438C · published 5 September 2026

Turn it off and let it thaw

Ice on an air conditioner in a Texas summer is not a cold problem. It is an airflow or a refrigerant problem, and running the system harder makes more ice, not less.

Switch the cooling off at the thermostat, but set the fan to On. That moves warm household air across the frozen coil and thaws it far faster than turning everything off. Expect one to three hours, and put towels down — all that ice becomes water and the drain pan may not cope with it at once.

Do not chip at it, and do not use a hairdryer or a heat gun. The coil is soft aluminium and thin copper. Puncture it and a $200 repair becomes a coil replacement, which on an older system is often the point where you are choosing between repair and a whole new system.

Why ice forms at all

The evaporator coil runs cold. It is meant to. What keeps it above freezing is a constant flow of warm household air across it.

Take that airflow away and the coil keeps getting colder until the moisture condensing on it freezes. Once a layer of ice forms, it insulates the coil, airflow drops further, and it snowballs — which is why people describe it as fine yesterday and a block of ice today.

The same thing happens if there is not enough refrigerant, for a different reason: low pressure means a lower boiling point, which means a colder coil than designed.

So it is one of two families

Airflow, which you can partly check. A blocked filter is the number one cause and it is a five-minute fix. Closed or blocked vents are next — people close vents in unused rooms to save money, and it does the opposite while starving the system. Then collapsed or leaking flexible ductwork, and a failing blower motor, both of which need us.

Refrigerant, which you cannot. Low charge means a leak, because the system is sealed. It needs gauges to confirm and a leak search to fix properly. Anyone who adds refrigerant to a frozen system without finding the leak has sold you next summer’s repair as well as this one.

There is a third, less common: running the AC when it is below about 60°F outside. Rare in a Texas summer, occasionally relevant in spring.

After it has thawed

Change the filter, open every vent, then run it and watch.

If it cools normally and stays clear, a blocked filter was your problem and you are done. If it freezes again within a day or two, the cause is refrigerant or something mechanical, and continuing to run it is wearing the compressor — liquid refrigerant returning to a compressor that expects gas is how compressors die.

That is the real cost of ignoring this one. The ice is not the damage; it is the warning about the damage.