Frozen coil: turn cooling off and let it thaw
Running the compressor with a frozen coil strains it toward failure. Trane's instruction is to switch the thermostat from COOL to OFF and not chip at the ice. Carrier says thawing takes 1 to 4 hours and to wait 3 to 4 hours before restarting.
What is probably happening
- Airflow is restricted: a clogged filter, blocked return vents, or a dirty evaporator coil. The coil gets too cold and ice builds.
- Or the system is low on refrigerant from a leak. Low charge makes the coil run below freezing.
- Ice on the copper line at the outdoor unit means the same thing is happening inside.
Do this in the next five minutes
- Thermostat to OFF, fan to ON. The fan pushes room air over the coil and melts it.
- Replace the filter now if it is dirty. Open every register.
- Put towels around the indoor unit. Melting ice makes a lot of water.
- Wait at least 3 to 4 hours, then set to COOL and see if it holds.
- If it freezes again with a clean filter, stop and call. That points to refrigerant or a coil problem.
Do not
- Do not chip or scrape the ice. It damages the coil fins.
- Do not run COOL while it is iced. That is what kills compressors.
- Do not accept a refrigerant top-off with no leak found. Low charge means it leaked out, and it will leak out again.
Who to call
A licensed HVAC technician, if it refreezes
Refrigerant work legally needs an EPA Section 608 certified technician. Only a technician can find and fix a leak and recharge to the manufacturer's spec.
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What it should cost
$250 to $1,500
Refrigerant leak repair, national range. A recharge on its own is $100 to $500; a coil replacement $600 to $2,400
Source: Angi, HVAC repair cost, updated August 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the hvac page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- What was the airflow and the temperature split when you tested it?
- If it is low on refrigerant, where is the leak, and will you fix the leak before recharging?
- What refrigerant is in this system, and what does it cost per pound today?
- What is your EPA Section 608 certification type?
End the call if
- A recharge with no leak search. The Department of Energy lists testing for leaks with a leak detector as part of a proper service visit.
- A full replacement quote when the only finding is a dirty filter or coil.