Why your AC freezes up in July, not January

A homeowner assumes a frozen evaporator coil means the system is low on refrigerant. Sometimes it does. More often, in a Tampa summer, it means something is blocking airflow across that coil — and adding refrigerant to a system that’s just cold and starved for air makes the problem worse, not better.

What’s actually restricting the airflow

Three things account for most frozen coils we see: a filter that hasn’t been changed in months, a blower motor running weaker than it should, or return ducts that are undersized or partially blocked. Any of the three slows the air moving across the coil enough that it drops below freezing and ices over — then melts, drips, and the cycle repeats.

Why turning it off first matters

If your coil is iced over, the fastest fix is also the cheapest: kill the system and let it thaw completely — six to eight hours, sometimes overnight — before anyone touches the refrigerant. Running a frozen system, or worse, chipping the ice off, risks damaging the coil itself. A technician needs to see it thawed to diagnose the real cause.

When it really is refrigerant

A slow refrigerant leak does cause icing, and it comes with its own signs: hissing at the line set, an oily residue at a fitting, or a system that ices up on a mild day, not just a scorching one. That’s a leak search and repair, not a filter swap — which is exactly why we check both before quoting either.