Ice on AC lines and water around the indoor unit: first steps

Ice on AC lines means switch the system off

When there is ice on AC lines and water around the indoor unit, set the thermostat to off. A frozen coil can't cool the house, and a system that keeps running while frozen can strain the compressor. The ice also melts into the drain pan faster than the drain can carry it away. That is how a frost problem turns into a puddle.

Switching off is the one step that limits the damage while you check the simple causes. Anything that involves refrigerant or wiring stays with a licensed contractor.

Why does the coil freeze up?

The indoor coil runs cold so it can pull heat and moisture out of the air. When too little warm air crosses it, the coil drops below freezing. Frost then builds on the coil and on the cold refrigerant line that leads to it. Low refrigerant from a leak can cause the same thing.

Airflow is the usual suspect, and it is the part a homeowner can check. Common causes include:

• The air filter is clogged with dust and lint.
• Supply vents are closed or blocked by furniture.
• A return grille is covered by a rug or a stack of boxes.
• The coil itself is dirty, or the blower is running weak.
• The refrigerant charge is low because of a leak.

Cooling demand adds up over a season. The NOAA weather station near Spanish Fork averages 1,013 cooling degree days a year, which is a measure of how much cooling the weather calls for. Every cooling day adds run time, and run time adds dust to the filter and coil. For the wider picture of how repairs work, see AC repair in Spanish Fork.

What can I safely check while it thaws?

Start with the checks that need no tools. Keep the thermostat on off while you work, so the system doesn't try to cool a frozen coil.

• Look at the air filter. If it is gray and packed with dust, replace it.
• Open every supply vent and uncover every return grille.
• Check that the outdoor unit has clear space around it, with no leaves, grass clippings or stored items against it.
• Confirm the thermostat display is working and the batteries are fresh.
• Look at the breaker. If it tripped, reset it once, but don't keep resetting it if it trips again.

Then give the ice time to melt all the way. Don't chip it, scrape it or pour hot water on it. A coil that still has frost on it will freeze again.

If the system also starts and stops in short bursts, short cycling explained covers that pattern.

Where does the water around the indoor unit come from?

Most of it is condensation. The coil pulls moisture out of the air, and that water drips into a pan and leaves through a drain line. Two things can overload that path: a frozen coil that melts all at once, or a drain line that is clogged with dust and algae.

Signs the drain line is the problem:

• Water sits in the pan even when there is no ice.
• A musty smell comes from the unit or the vents.
• A stain shows up on the ceiling or floor under the unit.
• The system shuts itself off, which can happen when a safety switch senses water.

Keep the system off while water is present. Soak up what you can reach with towels and set a shallow pan under any drip. If water is reaching anything electrical, leave the system off at the breaker and keep clear until a licensed contractor has looked at it.

Safety steps and work to leave alone

Some jobs near a frozen or wet unit are not for homeowners. A licensed contractor handles refrigerant, electrical parts and wiring, and sealed components. A licensed contractor also handles gas burners and valves if a furnace shares the same cabinet or closet. Opening panels to get at any of these is where a small problem becomes an injury or a bigger repair.

Two safety lines apply to any mechanical closet. If you smell gas, leave the house, then call the gas utility from outside. If a carbon monoxide alarm sounds, get everyone out and call emergency services.

Neither of these is a reason to wait for a repair call. They come first.

What should I note before I call?

A few details make the call easier. Jot them down while the unit thaws:

• When you first saw the ice or the water.
• Where the ice is: on the line outside the cabinet, on the coil, or both.
• What the thermostat was set to.
• The condition of the filter and when it was last changed.
• Whether the breaker tripped.
• Any new noise from the blower or the outdoor unit.

Where a contractor is available, the line connects the call to that contractor, who then confirms availability and fees.

Calling about a frozen AC coil

With the system off, the filter checked and the vents open, you have done what a homeowner safely can. The rest is for a licensed contractor.

We connect you with a licensed, insured HVAC contractor. For how the call works and what AC repair covers, read about AC repair in Spanish Fork.