Why Is My Commercial AC Freezing Up?

A frozen evaporator coil is one of the most common service calls we get for commercial rooftop units, especially during peak cooling season in San Antonio. When ice builds up on the coil, your system loses its ability to absorb heat, cooling capacity drops, and you risk serious compressor damage if it runs long enough.

The three most frequent culprits are restricted airflow, low refrigerant charge, and dirty coils. Clogged filters and blocked return grilles starve the coil of the warm air it needs to stay above freezing. A refrigerant leak lowers system pressure, which drops the coil temperature below the dew point. And a coil caked in dust simply cannot transfer heat efficiently.

If you spot ice on your unit, the first step is to shut off cooling and switch the fan to "on" to help thaw the coil. Then check and replace your filters. If the problem returns quickly, it is time to call a technician — chasing a refrigerant leak or diagnosing a failing blower motor is not a DIY job on commercial equipment.

The best defense is a preventative maintenance contract. Regular coil cleaning, filter changes, and refrigerant checks catch these issues before they shut your business down on the hottest day of the year.