Frozen AC coil

Frozen AC coil or iced lines in Oviedo, Florida

Ice on the indoor coil or the copper suction line means the coil is running below freezing, and that has two causes: not enough air across it, or not enough refrigerant in it. Switch the system to OFF, leave the fan on, and let it thaw. In Oviedo a blocked filter on an undersized 1980s return is the usual airflow cause.

Diagnosis

What is most likely wrong

Likely causes, ordered by how often they turn out to be the answer
#	Cause	How common	What it looks like
1	Blocked or excessively restrictive filter	Very common	The single most common cause. High-MERV pleated filters on an old return are a known offender.
2	Dirty evaporator coil	Very common	Years of dust and biological growth on the coil face. Weak airflow at every vent.
3	Low refrigerant charge from a leak	Common	Ice starts at the coil inlet or on the suction line outside. Needs gauges.
4	Failed or failing blower motor	Common	Air handler runs quietly or not at all while the outdoor unit runs.
5	Closed, blocked or crushed return path	Common	Furniture over the return grille, or a collapsed return flex in the attic.
6	Running the system below about 60°F outdoors	Less common	A January cold snap with the thermostat still on cool.
7	Wrong metering device or a mismatched coil	Less common	A changeout that paired the wrong indoor coil with the new condenser.

Before you call

What you can safely check yourself

Switch the system to OFF and the fan to ON. Give it several hours to thaw. Do not chip at the ice.
Replace the filter, and if it was a dense pleated filter on an old system, try a less restrictive one.
Clear every return grille of furniture and rugs.
Once thawed, watch the air handler: if the blower runs and the ice comes back within a day, it is charge or coil, and it needs a licensed tech.
Check the secondary drain pan after the thaw — a frozen coil dumps a lot of water at once and can trip the float switch.

Where the licensed line is

Refrigerant, capacitors and the inside of an electrical panel are not homeowner jobs. A run capacitor holds a lethal voltage after the disconnect is pulled. Refrigerant handling requires EPA Section 608 certification. And in Florida the work itself is regulated: an air conditioning contractor licensed under Chapter 489 may replace, disconnect and reconnect the power wiring at the dedicated disconnect, and repair or replace disconnects, breakers and fuses on dedicated HVAC circuits — s. 489.105(3). Verify any Florida contractor’s licence, including ours, at DBPR Verify a Licensee.

In Oviedo

Why this happens in this housing stock

Airflow is the Oviedo cause because of the returns. The 25.0% of the city built 1970–89 — Alafaya Woods above all — was commonly built with one central return sized for 1986 equipment. That return is already near its limit with a clean filter; a dense pleated filter, or six weeks of a nine-month season without a change, takes it past the limit and the coil freezes. The fix is often a second return, not a refrigerant call.

The refrigerant cause carries a second decision in this stock. If the system is R-410A and the leak is in the evaporator coil, the repair is $700–$2,500+ on a refrigerant that is being phased down. On a system past twelve years that is usually where the repair-or-replace arithmetic gets done properly, and on the Duke side of the river a strip-heat house forfeits a published rebate by repairing.

Housing stock: Seminole County Property Appraiser CAMA extract, Parcels.csv dated 5 September 2026. Median build year 1995; 25.0% of parcels built 1970–89; 39.4% with a pool.

Cost

What the fix typically costs

Researched repair ranges for this symptom, 2026
Job	Researched range	Notes
Diagnostic visit, national	$75–$150	This Old House 2026. A competing Oviedo contractor publishes $89, waived with a completed repair.
Evaporator coil cleaning or replacement	$700–$2,500+	Cleaning at the bottom of the band, replacement at the top.
Refrigerant leak repair	$200–$1,500+	Finding the leak is most of the cost; weigh it against the R-410A phase-down.
Blower or condenser fan motor	$300–$800	ECM motors at the top of the band; a PSC motor in a 1986 air handler at the bottom.
Duct repairs or modifications	$500–$1,500	Florida cost guide; the duct allowance on an Oviedo changeout.

Read this before you use any number on this page. Every figure here is a researched third-party market range with its source and capture date named beside it. None of them are a contractor’s price and none of them are a quote. They are here so you can sanity-check a quote you have already been given.

Not getting anywhere?

Tell us the symptom, the build year of the house and roughly how old the equipment is. That usually narrows it to two candidates before anyone drives out.

Call (321) 415-3018 Send the address and build year

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