Estimated Read Time: 9 minutes
When your AC is running but not cooling, every minute in Florida heat feels longer. If your thermostat reads 78 but the house sits at 84, this guide explains why and how to fix it fast. Below are the seven most common causes we see in coastal homes, what you can safely check today, and when to call Del-Air for professional AC repair that restores chill without surprises.
1) Clogged or Restricted Airflow
If the system cannot breathe, it cannot cool. Dirty filters, blocked return grilles, closed supply vents, or crushed flex duct cut airflow and lower coil temperature until it ices over. Once ice forms, cooling falls off a cliff.
What you can check now:
- Replace or clean the filter. In peak summer, monthly changes are smart.
- Open all supply vents and clear furniture from returns.
- Look for collapsed or kinked duct runs in the attic.
Florida insight: In coastal areas like Vero Beach and Jupiter, fine sand and high pollen seasons load filters quickly. A MERV 8–11 filter balanced for airflow is often the sweet spot. Oversized high-MERV filters can choke older systems.
When to call a pro: If the indoor coil is frozen, power the system off at the thermostat and let it thaw for 6–8 hours. Running a frozen system risks compressor damage. We can correct static pressure problems, repair ducts, and recalibrate airflow so your system cools to spec.
2) Dirty Coils Reduce Heat Transfer
Your AC removes heat indoors and rejects it outdoors. Dirt on either coil acts like a blanket on that heat exchange. Florida’s salt air accelerates film build-up on outdoor condenser fins, and kitchen aerosols plus dust cling to indoor coils.
What you can check now:
- Gently rinse the outdoor unit fins with a garden hose from the inside out. Power off first.
- Keep 18–24 inches of clear space around the condenser. Trim hedges and remove mulch piled against the base.
Local detail: Homes near the Intracoastal or the beach see faster corrosion. A fresh-water rinse schedule and protective coatings can extend coil life.
When to call a pro: If you see matted fins or a greasy coil, professional cleaning with the right coil-safe chemicals restores capacity. We also check refrigerant charge and fan performance so you do not mask a deeper issue.
3) Low Refrigerant or a Leak
Refrigerant is the heat carrier. Low charge reduces cooling capacity and can cause the evaporator to ice. It does not get “used up,” so if it is low, there is a leak.
What you can check now:
- Listen for hissing at the indoor or outdoor unit.
- Look for oily residue at service ports or coil joints.
- Note if cooling improves at night. Marginal charge often struggles in daytime heat.
Florida insight: Vibration from daily afternoon storms and salt corrosion on braze joints can accelerate leaks. Catching a small leak early is far cheaper than replacing a burnt-out compressor later.
When to call a pro: We perform a full diagnostic, pressure test, and electronic leak search. If a repair is viable, we fix the leak, verify vacuum integrity, and recharge to manufacturer specs. If coils are failing, we price repair versus replacement with upfront numbers so you choose the best long-term value.
4) Thermostat or Electrical Issues
If your system runs but cannot reach setpoint, the problem might be control related. Miscalibrated thermostats, failed temperature sensors, weak capacitors, and loose electrical connections are common.
What you can check now:
- Make sure the thermostat is on Cool and set at least 3 degrees below room temp.
- Replace thermostat batteries. Low voltage causes erratic behavior.
- Verify the fan is set to Auto, not On, which can blow warm air between cycles.
Local detail: Rapid power blips during summer storms are tough on capacitors and contactors. A $15 surge strip does not protect your condenser. A whole-home surge protector is the right tool.
When to call a pro: Electrical diagnostics are not DIY. Our licensed technicians check voltage, amperage, capacitors, contactors, and tighten connections. We correct the root cause so the issue does not return during the next heatwave.
5) Clogged Condensate Drain or Safety Switch Trip
Your AC removes gallons of moisture on humid days. That water exits through a condensate line. Algae, sludge, or a sag in the line can clog the drain and trip a float switch. The system may run the fan but disable cooling to prevent overflow.
What you can check now:
- Inspect the drain line near the air handler. If you see standing water, shut off the system.
- Pour a cup of white vinegar into the maintenance tee to discourage algae.
- Check for water in the secondary drain pan in the attic.
Florida insight: Warm, humid attics in Palm Bay, Lake Worth, and along the Treasure Coast are perfect for algae growth. Annual drain line service and a safe drain treatment keep water moving.
When to call a pro: We clear the line with proper suction or nitrogen, verify slope, treat for algae, and test float switches. We also look for hidden rust that signals a pan replacement before a ceiling stain becomes a ceiling repair.
6) Undersized, Oversized, or Aging Equipment
A unit that runs all day yet barely cools may be mismatched to the home or nearing the end of its life. Additions without duct changes, leaky old windows, or a unit that is too large can all cause comfort problems. Oversized systems short-cycle and fail to dehumidify, so it feels sticky and warm.
What you can check now:
- Think about recent changes: new sunroom, insulation, or window upgrades.
- Track runtime on the hottest afternoons. Continuous runtime with poor cooling signals a capacity or duct issue.
Local detail: In West Palm Beach and Boca Raton, west-facing rooms cook in late sun. Zoning or a duct balance can fix hot-room complaints without replacing the whole system.
When to call a pro: We run a proper Manual J load calculation, inspect ducts for leakage, and measure static pressure. If replacement makes sense, we provide options sized to your home’s real needs, not just the model you had before.
7) Duct Leaks and Attic Heat Gain
If you pay to cool air that never reaches the rooms, comfort drops and bills rise. Leaky supply ducts dump cold air into a 130-degree attic. Return leaks pull in dusty, hot attic air and overwhelm the system.
What you can check now:
- Feel for air movement at visible duct joints when the system runs.
- Look for missing mastic or loose tape at connections.
- Note rooms with weak airflow compared to others.
Local detail: Older homes in Melbourne and Port Saint Lucie often have taped-only joints. Proper sealing with mastic and a pressure test can recover 10–30 percent of lost capacity depending on leakage severity.
When to call a pro: We pressure-test the system, seal with mastic, and verify airflow at each register. Balancing fixes comfort room by room.
Quick Fixes You Can Try Today
- Replace the filter and set the thermostat to Auto.
- Rinse the outdoor coil and clear shrubs.
- Pour vinegar in the condensate tee.
- Give the system a full power reset at the breaker for 2 minutes if safe to do so.
- If ice is present, power off and let it thaw before attempting further cooling.
If those do not help, schedule a diagnostic. The sooner you act, the more you protect the compressor and avoid secondary damage.
Why Homeowners Choose Del-Air for AC Not Cooling
- 24/7 emergency response and same-day service windows when the heat index soars.
- Decades of Florida coastal experience since 1983, including salt-air and corrosion prevention.
- Licensed, bonded, insured technicians who service all brands and system types: central AC, heat pumps, mini-splits, and packaged units.
- Transparent pricing and repair-versus-replacement guidance so you know every option before approving work.
- Maintenance Agreement Plan built for Florida homes: two annual tune-ups, free diagnostics with service visits, 15% off repairs, $500 off AC and heating installations, no overtime or weekend fees, and a 100% satisfaction guarantee.
Hard facts that protect you:
- Licenses: EC13013085, CAC1822274, CAC051477, CFC057524. Work is code-compliant and permit-ready.
- The Maintenance Agreement includes two visits per year and 15% off repairs, which often saves more than the plan cost for active systems in high-humidity zones.
Service coverage: We help homeowners across Palm Bay, West Palm Beach, Boca Raton, Melbourne, Port Saint Lucie, Boynton Beach, Lake Worth, Wellington, Jupiter, and Palm Beach Gardens. If your AC is running but not cooling, we likely have a tech near you today.
Special Offer: Free Trip Charge With Paid Repair
Save on today’s AC repair. Use code FREE TRIP CHARGE WITH PAID REPAIR before Jul 31, 2026. Terms and conditions may apply. Call (772) 567-3100 or book at https://www.delair.com/vero-beach/ to lock in your appointment and apply the offer.
What Homeowners Are Saying
"The technician showed up right on time, was respectful, and knew exactly what he was doing. He explained the issue and had my AC running like new in no time. Even got a follow up call to check on me the next day. All in all, solid"
–John S., AC Repair
"If you want a friendly professional team who will take care of you, Del-Air is your company! Super friendly, easy to talk to, and easy to understand from the moment they arrived. Our AC system was fixed that day and we will definitely use Del-Air again."
–Dean D., Vero Beach
Frequently Asked Questions
Why is my AC running but not cooling after a storm?
Power blips can weaken capacitors or trip a float switch. Try a safe breaker reset once. If warm air continues, schedule a diagnostic to test electrical and drains.
How long should my AC run to reach setpoint?
On a 95-degree day, continuous runtime for an hour or more can be normal. If rooms stay above setpoint by 3 degrees or more, you likely have airflow, charge, or duct issues.
Can a dirty filter really stop cooling?
Yes. A clogged filter starves airflow, drops coil temperature, and can cause icing. Replace filters monthly in summer or more often in dusty or coastal homes.
Is low refrigerant always a replacement?
No. If the leak is accessible, we repair and recharge to spec. If the coil is failing, we compare repair versus replacement with clear pricing and warranties.
What maintenance prevents “running but not cooling” problems?
Two tune-ups per year in Florida are ideal. Coil cleaning, electrical checks, drain service, and refrigerant verification catch small issues before comfort drops.
Bottom Line
If your AC is running but not cooling, start with airflow, coils, drains, and controls. Florida’s heat and humidity make small issues snowball fast. Del-Air restores comfort with same-day diagnostics and solutions tailored to coastal homes.
Ready to Get Cool Again?
Call (772) 567-3100 or schedule at https://www.delair.com/vero-beach/. Mention Free Trip Charge with Paid Repair to save on today’s service. Serving Palm Bay, West Palm Beach, Boca Raton, Melbourne, Port Saint Lucie, and nearby communities.
Schedule Your AC Repair Now
- Call: (772) 567-3100
- Online: https://www.delair.com/vero-beach/
- Offer: Free Trip Charge with Paid Repair through Jul 31, 2026
Book today for fast, expert AC repair and clear, upfront pricing that gets your home comfortable again fast.
About Del-Air Heating, Air Conditioning, Plumbing and Electrical
Since 1983, Del-Air has kept Florida homes comfortable with licensed, background-checked technicians and same-day service. We service all brands, offer 24/7 emergency response, upfront pricing, and flexible financing. As one of Florida’s largest residential HVAC providers, we back our work with a 100% satisfaction guarantee. Licenses: EC13013085 | CAC1822274 | CAC051477 | CFC057524.