Lone Star Cooling and Heating
Get help with Frozen AC Coil
Call Lone Star Cooling and Heating, have us call you, or describe the issue.
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Call (325) 219-0005Ice on the indoor coil or the copper refrigerant lines, thawed out and traced to its cause, which is almost always too little air moving across the coil or too little refrigerant in the system.
01Frozen coil
A frozen coil is usually hidden inside the equipment. These are the signs that show on the outside.
Frost on the larger copper line near the indoor or outdoor unit usually means the coil it comes from has frozen. The system needs to be switched off to thaw, and the airflow or charge problem behind the ice found.
As ice builds on the indoor coil it blocks the air trying to pass through, so airflow drops and the air that does get through carries less cooling. It often gets worse over a day of running.
When a frozen system shuts off, the ice melts all at once and can flood the drain pan. Water that shows up after cooling stops, rather than while it runs, often points back to a frozen coil.
Ice that returns after a thaw means its cause is still there. Once the filter and vents are ruled out, a refrigerant leak or a failing blower becomes more likely.
02Air or refrigerant
Nearly every frozen coil comes back to one of these two. Which one it is decides the repair.
A clogged filter, a dirty indoor coil, closed or blocked vents and returns, a slipping or failing blower, or a collapsed duct all starve the coil of warm air. Without that heat to absorb, it drops below freezing. Restoring the airflow usually ends the icing.
When the charge is low, the pressure in the coil falls and so does its temperature, until moisture freezes on it. Low charge means a leak, so adding refrigerant alone does not solve it. A restriction in the refrigerant circuit can cause the same pattern and is checked alongside.
None of this finds the cause. All of it lets the coil thaw without doing more damage.
Set the thermostat to off so the compressor stops. Setting the fan alone to on, where the thermostat allows it, moves room air across the coil and helps it thaw.
Leave the ice where it is. Chipping or scraping at it can puncture the coil or the fins and turn an airflow problem into a refrigerant leak.
A thawing coil releases a lot of water at once. Keep people away from any that spreads near the unit or outlets, and mention it when calling.
Frozen AC Coil
Serving Abilene, TX.
03Why it waits
A frozen coil disguises its own cause, which is why the first step is patience.
While the coil is frozen, the ice itself blocks airflow and changes the pressures and temperatures in the system, so a clogged filter and a refrigerant leak produce nearly the same readings. Measuring then would point at the ice rather than whatever caused it. Once the coil is clear and the system has run for a while, the real airflow and the true charge can be read.
Running a frozen system is the thing to avoid. It barely cools, the ice keeps spreading back along the lines, and liquid refrigerant that never boiled off in the coil can reach the compressor, which is built to pump vapor. A frozen coil caught early is usually a modest repair; one run frozen for days can become a much larger one.
04Questions
The indoor coil runs colder than the room air on purpose. If too little air moves across it, or the system is short of refrigerant, the coil gets colder still and the moisture on it turns to ice. The weather outside does not prevent it.
Ice changes every reading the diagnosis depends on. Airflow, pressures and temperatures all look wrong while the coil is frozen, whatever the cause. Once it has thawed, the system can run normally long enough to show what is actually happening.
Yes. It cools very little, the ice keeps growing, and refrigerant that should have turned to vapor in the coil can return to the compressor as liquid, which can damage it. It also leaves a lot of water to drain once it stops.
If it smells of burning, is leaking water, or the outdoor unit is humming without its fan turning, yes: switch it off at the thermostat. A system that runs but does not keep up can usually stay on until it is looked at.
Lone Star Cooling and Heating
Call Lone Star Cooling and Heating, have us call you, or describe the issue.
Prefer to talk?
Call (325) 219-0005