AC Running but Not Cooling? 7 Things to Check First

Key takeaways

• Check the simple stuff first. A dirty filter, blocked vents, or wrong thermostat setting can make an AC run nonstop without cooling and are easy, low- or no-cost fixes.
• Some issues are DIY-safe, others are not. Basic checks like filters and outdoor debris are fine for most homeowners; anything involving refrigerant, electrical parts, or opening the unit should be left to a licensed HVAC pro.
• Typical repair visits run a few hundred dollars. Many common AC cooling issues fall in the $150–$600 range, but major problems (like a bad compressor) can reach $1,500+ and push you toward replacement.
• Age of your system matters. If your AC is 10–15+ years old and needs a big repair, it’s often smarter to put that money toward a new, more efficient unit.
• Efficiency affects your monthly bills. A properly working, well-maintained AC can cut energy use, while a struggling unit can quietly add $20–$60+ per month to your electric bill.
• Get multiple quotes for bigger decisions. For anything over a few hundred dollars, it’s wise to get 2–3 estimates to compare repair options, warranties, and replacement pricing.

Typical price range

All numbers below are approximate US ballpark ranges for central AC systems. Window and portable units are usually cheaper to repair or replace.

• Service call / diagnosis: $75–$200
  • Often includes basic troubleshooting; parts and labor are extra.
• Thermostat issue (simple repair or replacement): $100–$350
  • Depends on whether it’s a basic or more advanced thermostat.
• Clogged drain line / frozen coil (simple fix): $150–$400
  • Includes clearing the drain, thawing coils, and basic cleaning.
• Electrical components (capacitor, contactor, relay): $150–$500
  • Parts are usually inexpensive; labor and access drive the total.
• Refrigerant leak check and recharge: $300–$900+
  • Costs vary by refrigerant type, amount needed, and whether a leak is repaired.
• Blower motor or fan motor replacement: $400–$1,200
  • Higher-end, variable-speed motors land at the upper end.
• Major repair / borderline replacement (coil, compressor): $1,200–$3,500+
  • At this level, replacing the entire system may start to make more sense.
• Full AC replacement (central system only): $5,000–$12,000+
  • Wide range based on size, efficiency, ductwork condition, and region.

What pushes costs lower

• Newer system (under ~8 years). Parts are easier to source and usually cheaper.
• Simple issues. Dirty filters, blocked vents, tripped breakers, or a minor electrical part.
• Good access. Outdoor unit and indoor air handler that are easy to reach.
• Existing warranties. Parts may be covered, leaving you to pay mostly labor.

What pushes costs higher

• Older equipment. Systems 10–15+ years old often need pricier parts and more labor.
• Refrigerant type. Older refrigerants can be more expensive and harder to find.
• Hidden damage. Water damage, mold, or burnt wiring discovered during diagnosis.
• After-hours or emergency calls. Nights, weekends, and holidays usually cost more.
• Difficult access. Tight attics, crawlspaces, or roof-mounted units increase labor time.

Repair vs. replacement

When your AC is running but not cooling, you’re often deciding between a targeted repair and putting that money toward a new system.

When repair usually makes sense

• System age is under 10 years.
• Repair cost is under ~30% of a new system (for example, under $1,500 if replacement would be around $5,000).
• Problem is clearly defined and fixable, like a bad capacitor, clogged drain, or faulty thermostat.
• You’re happy with current comfort and bills, and just want it working again.

When replacement is worth considering

• System is 12–15+ years old. Many central AC units last about 12–18 years with good maintenance.
• Repair estimate is over ~40–50% of replacement cost.
  • Example: If a new system would be $8,000, and your repair quote is $3,500, replacement should be on the table.
• Frequent breakdowns. If you’ve had multiple repairs in the last 2–3 summers, ongoing costs may exceed the price of a new unit.
• High energy bills and uneven cooling. An older, inefficient system can cost you hundreds per year in extra electricity.

A concrete example

• Your 13-year-old AC stops cooling.
• The tech quotes $2,000 to replace a leaking coil and recharge refrigerant.
• A comparable new, mid-range system is estimated at $7,000 installed.

While repairing is cheaper today, you’re putting ~30% of replacement cost into an older unit that might only last a few more years and still be inefficient. In this case, many homeowners choose replacement to avoid repeated repairs and to lower energy bills.

Efficiency and long-term costs

Even if you’re in “just get it working” mode, it helps to think about operating cost and lifespan, not just today’s bill.

• Struggling AC = higher bills. If the system runs constantly and barely cools, it can add $20–$60+ per month to your summer electric bill.
• Dirty coils and filters waste energy. A simple cleaning and filter change can improve efficiency and comfort with a relatively small service fee.
• Higher-efficiency units cost more upfront. But they can save hundreds per year in electricity, especially in hot climates or large homes.
• Right-sized equipment lasts longer. An oversized or undersized system short-cycles or runs nonstop, wearing out parts faster.
• Regular maintenance pays off. An annual tune-up (often $100–$250) can catch small issues before they become major breakdowns.

If your current AC is older and inefficient, a planned replacement in the off-season can be more cost-effective than a rushed emergency install in peak summer.

What to expect from a visit or project

Before the pro arrives

• Confirm the basics.
  • Thermostat is set to “Cool” and a temperature lower than the room.
  • Breakers for the AC and air handler/furnace are not tripped.
• Clear access.
  • Move items away from the indoor unit, vents, and thermostat.
  • Clear debris and clutter around the outdoor condenser.
• Note symptoms.
  • When did the problem start?
  • Is air blowing but warm, or is there no airflow at all?
  • Any unusual noises, smells, or water leaks?

Typical repair visit

Most repair visits take 1–3 hours, depending on the issue.

• Initial conversation (5–10 minutes).
  • You describe the problem and any recent work or changes.
• Basic checks (10–30 minutes).
  • Thermostat settings, air filter, breakers, and visible wiring.
  • Indoor and outdoor units inspected for ice, debris, or obvious damage.
• Detailed diagnosis (20–60+ minutes).
  • Measuring temperatures and pressures.
  • Checking electrical components (capacitors, contactors, relays).
  • Looking for refrigerant leaks or clogged drain lines.
• Estimate and options (10–20 minutes).
  • The tech explains what’s wrong, recommended repairs, and estimated costs.
  • You approve or decline work before parts are installed.
• Repair and testing (30–90+ minutes).
  • Parts replaced or cleaned.
  • System restarted and monitored to ensure it’s cooling properly.
• Wrap-up (10–15 minutes).
  • Review what was done, any maintenance tips, and warranty details.
  • You receive an invoice and possibly a written report.

Typical replacement project

A full AC replacement usually takes 1 day, sometimes 2 days for more complex setups.

• Pre-visit / estimate.
  • The pro inspects your existing system, measures your home, and discusses comfort issues.
  • You receive a written quote with equipment options and warranties.
• Installation day (6–10 hours).
  • Old equipment is removed and properly disposed of.
  • New indoor and outdoor units are installed, connected, and wired.
  • Refrigerant lines are vacuumed and charged to the correct level.
  • System is started and tested for cooling performance and safety.
• Final walkthrough (15–30 minutes).
  • The installer shows you how to use the thermostat and change filters.
  • You review documentation, warranties, and recommended maintenance.

DIY vs. hire a pro

Reasonable DIY checks (for most homeowners)

These are generally safe as long as you turn off power where appropriate and don’t open sealed panels:

• Check and change the air filter.
  • A clogged filter can severely restrict airflow and cooling.
• Verify thermostat settings.
  • Make sure it’s on “Cool”, set below room temperature, and not in a weird mode (like “Fan Only”).
• Inspect and clear vents.
  • Ensure supply and return vents are open and not blocked by furniture or rugs.
• Check the outdoor unit.
  • Gently remove leaves, grass clippings, and debris from around the condenser.
  • Do not bend fins or spray water directly into electrical components.
• Check the breaker.
  • If the AC breaker is tripped, you can reset it once. If it trips again, call a pro.

Tasks to leave to licensed pros

Because of shock, fire, refrigerant, and code risks, these should be handled by trained HVAC technicians:

• Refrigerant work.
  • Finding and fixing leaks, recharging, or changing refrigerant types.
• Opening electrical panels or junction boxes.
  • High-voltage components can cause serious injury.
• Replacing capacitors, contactors, motors, or compressors.
  • Incorrect parts or installation can damage the system or create fire hazards.
• Accessing sealed components or coils.
  • Mishandling can cause leaks, damage fins, or void warranties.
• Modifying ductwork or structural elements.
  • Poorly done duct changes can hurt efficiency and violate building codes.

If you’re ever unsure, err on the side of calling a pro. You can use a neutral directory like Home Services Scout to compare local HVAC technicians and read reviews.

Questions to ask potential pros

• “What do you charge for a diagnostic visit, and what does it include?”
• “Can you walk me through what you’ll check before recommending a repair?”
• “Is this issue likely a one-time problem, or a sign of a bigger underlying issue?”
• “Are parts and labor under warranty, and for how long?”
• “If I put this much into a repair, how long do you expect the system to last?”
• “Can you provide a written estimate before starting any major work?”
• “Are there lower-cost repair options, and what are the trade-offs?”
• “If I replaced the system instead, what would a ballpark cost and efficiency rating look like?”
• “Will this repair improve my energy efficiency, or just get me by?”
• “Do you offer maintenance plans, and what do they cover?”
• “Are you licensed and insured for HVAC work in this area?”
• “Will any of this work require permits or inspections?”

Quick FAQ

Why is my AC running but blowing warm air?

Common causes include incorrect thermostat settings, a dirty filter, low refrigerant, a frozen coil, or a failing compressor or fan. You can safely check the thermostat, filter, and vents; anything beyond that should be diagnosed by a pro.

Can I keep running the AC if it’s not cooling?

It’s usually not a good idea. Running the system while it’s struggling can damage the compressor, waste energy, and worsen issues like ice buildup or leaks. Turn it off and call an HVAC technician if basic checks don’t solve it.

How long should my central AC last?

Most central AC systems last around 12–18 years with regular maintenance. Heavy use, poor maintenance, or incorrect sizing can shorten that lifespan.

Will my homeowner’s insurance cover AC repairs?

Insurance typically does not cover normal wear-and-tear or age-related failures. It may help if the damage is from a covered event (like a storm or fire). Warranty coverage and home service plans are separate and have their own rules.

Wrap-up / next steps

When your AC is running but not cooling, start with safe, simple checks: thermostat, filter, vents, and outdoor debris. If those don’t fix it, the next step is usually a professional diagnosis, especially for anything involving refrigerant or electrical parts.

Keep the age of your system, cost of the repair, and your energy bills in mind:

• Younger system + modest repair cost → repair usually makes sense.
• Older system + expensive repair → consider whether replacement will save money and stress over the next few years.

For any repair or replacement over a few hundred dollars, it’s smart to get 2–3 quotes so you can compare pricing, options, and warranties. A neutral directory like Home Services Scout can help you quickly find and compare local HVAC pros.

With a clear plan and the right help, you can get your home comfortable again and make a decision that fits both your budget and your long-term peace of mind.