AC Not Cooling? Top 5 Reasons and What To Do

Category: AC Repair / Troubleshooting

AC Not Cooling? Top 5 Reasons — And What To Do About Each

It’s one of the most frustrating experiences a Florida homeowner can have: your air conditioner is running, you can hear it working, the fan is blowing — but your house just isn’t getting cool. The thermostat says 74°F but your home feels like 82°F. You’ve turned it up, then back down, turned the whole thing off and on again. Nothing.

This is one of the most common calls we receive at Elite AC LLC throughout Jacksonville and Central Florida, especially when temperatures start climbing in late spring. The good news: in most cases, there’s a specific, diagnosable cause — and often a same-day fix.

Here are the five most common reasons an air conditioner runs but doesn’t cool properly, what each means, and what you should do.

Reason 1: Dirty Air Filter

The symptom: System runs, airflow from vents feels weak, cooling is inadequate.

This is the most common cause of poor cooling in Jacksonville area homes — and the most preventable. When an air filter becomes heavily clogged with dust, pollen, and debris, it restricts airflow through the system so severely that the AC cannot move enough conditioned air to cool the space.

In severe cases, a clogged filter can cause the evaporator coil to freeze over. Ice forms on the coil because there’s insufficient warm air moving across it. Ironically, a frozen evaporator coil means less cooling, not more — the ice acts as an insulator.

What to do: Check your filter. If it’s gray, packed with debris, or you can’t see light through it, replace it immediately. For a frozen coil, turn the system to “fan only” mode (not cooling) for several hours to let the ice melt before resuming normal operation. Then address the filter.

Jacksonville’s pollen season — especially oak pollen from February through May — is intense. One-inch filters can clog in three weeks during peak pollen periods. Check yours monthly.

Reason 2: Low Refrigerant (Refrigerant Leak)

The symptom: System runs continuously, house never reaches set temperature, warm air from vents even after extended runtime, possible ice on refrigerant lines near the air handler.

Refrigerant is the substance that makes air conditioning work — it absorbs heat from inside your home and releases it outside. When your system is low on refrigerant, it cannot transfer heat effectively. The result: the compressor runs continuously, the system works overtime, and your home stays warm.

Contrary to a common misconception, refrigerant doesn’t “get used up” like gasoline. A properly functioning system has the same charge it left the factory with. If your refrigerant is low, you have a leak somewhere in the system — a pinhole in a copper line, a failing valve, a corroded fitting.

For Jacksonville Beach, Atlantic Beach, and Neptune Beach homeowners, salt air is a significant contributor to refrigerant line corrosion. Coastal properties see refrigerant leaks at a higher rate than inland homes.

What to do: Call a licensed HVAC technician. Adding refrigerant without finding and repairing the leak is like filling a tire with a nail in it — it’ll just leak out again. A proper repair involves locating the leak, repairing or replacing the affected component, and then recharging the system to the correct specification.

Reason 3: Dirty Evaporator or Condenser Coils

The symptom: System runs, cooling is inefficient or insufficient, possibly higher energy bills.

Your AC system has two coils: the evaporator coil (inside the air handler) and the condenser coil (in the outdoor unit). Both coils transfer heat — and both accumulate dirt, dust, pollen, and debris over time.

A dirty coil is like putting a blanket over a radiator. The coating of grime acts as insulation, reducing the coil’s ability to transfer heat. A condenser coil that’s only 30% coated with debris can reduce your system’s efficiency by 30% or more — meaning the same electricity produces significantly less cooling.

In Jacksonville, oak pollen season creates heavy condenser coil fouling. Homes near the beach deal with fine salt spray that accelerates buildup. Near I-10, I-95, and other high-traffic corridors, automotive particulates contribute to faster accumulation.

What to do: Condenser coil cleaning is part of a professional tune-up. You can spray the outside of the condenser unit gently with a garden hose (from the inside out if possible) to remove loose debris, but thorough coil cleaning with the appropriate chemical cleaner requires professional service.

Reason 4: Failed Capacitor

The symptom: AC won’t start at all, makes a humming noise but the fan or compressor doesn’t spin up, or system runs briefly and shuts down.

Capacitors are cylindrical electrical components that store and release energy to start the compressor and fan motors in your outdoor unit. They’re one of the most frequently replaced components in Florida HVAC systems — and one of the most common causes of sudden cooling failure, especially on the hottest days of the year.

Here’s the cruel physics of capacitor failure: capacitors degrade faster under heat stress, which means they’re most likely to fail on the hottest day of summer — when your system is working hardest and you need it most. When a capacitor fails, the motor it serves can’t start. The system either won’t turn on at all, or you’ll hear the outdoor unit humming but see the fan not spinning.

In Jacksonville and all of Northeast Florida, where summer temperatures regularly hit 95°F+ and outdoor units bake in full sun, capacitor failure is one of our most common summer service calls.

What to do: This is a professional repair — capacitors hold significant electrical charge and are dangerous to handle without proper training and equipment. The good news: capacitor replacement is typically a same-day repair that our technicians carry on their service vehicles.

Reason 5: Refrigerant Overcharge or Undersized System

The symptom: System runs constantly but can’t cool to the set temperature, or system cools but the house feels clammy and humid even when the temperature is right.

Two different problems with similar outcomes:

Undersized system: If your home has had additions, significant window replacements, or insulation changes — or if the original system was simply undersized — the unit may not have enough capacity to cool your home effectively in Jacksonville’s peak heat. A 2.5-ton system trying to cool a home that needs 4 tons will run constantly and never keep up on a 95°F afternoon.

Oversized system: Paradoxically, an oversized system creates a different problem — the home feels humid even when the temperature is acceptable. An oversized system cools the air so quickly that it shuts off before running long enough to remove significant humidity. Jacksonville’s humidity makes this a common complaint in homes where a previous owner replaced the system with a “bigger is better” approach.

What to do: If you’ve already addressed filters, coils, and refrigerant and still can’t keep up with the heat, a load calculation assessment is the next step. A properly licensed HVAC company will measure your home and calculate the correct tonnage — not guess.

When to Call for AC Repair in Jacksonville

Call immediately if:
– Your system has stopped working entirely
– You see ice forming on refrigerant lines or the outdoor unit
– You hear grinding, squealing, or banging from the outdoor unit
– Your home is reaching dangerous temperatures (above 85°F) with vulnerable household members

Call same-day if:
– Your system runs but can’t keep the temperature within 3–4°F of the set point on a typical summer day
– You’ve replaced the filter and the problem persists
– Your energy bills have spiked significantly without explanation

Schedule for this week if:
– Your system is working but you’re noticing reduced performance compared to previous summers
– It’s been more than a year since your last maintenance visit
– Your system is more than 10 years old and hasn’t been serviced recently

Get Your Jacksonville AC Running Right

Elite AC LLC serves Jacksonville, Orange Park, Fleming Island, the Beaches communities, Ponte Vedra, St. Augustine, Palm Coast, and all of Northeast Florida with same-day HVAC repair service. We also serve Central Florida through our Longwood hub.

Don’t spend another Florida summer sweating it out. Call us and let’s fix it.

📞 Northeast Florida (Jacksonville): (904) 420-0075
📞 Central Florida (Orlando/Longwood): (407) 602-7733
Available 7 days a week. Emergency service 24/7. License: CAC1818659.

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