AC Not Cooling? 7 Checks Before You Call for Repair

Start here: 10 minutes, no tools required

Before assuming something is broken, rule out the simple stuff. These checks take a few minutes each and account for a large share of 'AC not cooling' calls.

1. 1Check the thermostat. Confirm it's set to COOL (not FAN or HEAT) and the target temperature is set below the current room temperature. If the display is dim or blank, swap in fresh batteries — a dying thermostat battery can cause erratic or no cooling calls even though the screen still lights up.
2. 2Check the breaker and any disconnect switches. Your AC typically has two power points: a breaker in the main electrical panel and a shutoff switch or fused disconnect near the outdoor unit. If either has tripped or been switched off, the indoor blower may run while the outdoor unit does nothing — which feels exactly like 'it's blowing, just not cold.'
3. 3Pull the air filter and look at it in daylight. This is the single most common cause of weak or absent cooling. A clogged filter starves the system of airflow, which can drop the coil below freezing and shut cooling down entirely. If you can't see light through it, replace it.
4. 4Walk the house and check your vents. Make sure supply vents (where air comes out) aren't closed or blocked by furniture, rugs, or curtains, and that the return vent (usually one large grille, often in a hallway or ceiling) is unobstructed. Closing off too many rooms restricts the whole system's airflow, not just that room's.
5. 5Look at the outdoor condenser unit. It needs clear airflow on all sides. Clear away grass clippings, leaves, mulch, or overgrown shrubs, and leave at least a couple feet of open space around it. A condenser that can't breathe can't reject heat, which means the refrigerant can't cool your air.
6. 6Check for ice on the indoor coil or the refrigerant line. Open the indoor unit or air handler if you can do so safely, or look at the larger (insulated) copper line running to the outdoor unit. If you see frost or ice, turn the system off completely (not just to fan) and let it thaw for a few hours before running it again. Running a frozen system continues to restrict airflow and can push liquid refrigerant back toward the compressor, which risks real damage.
7. 7Check the condensate drain and float switch. Central AC systems produce a steady drip of condensation that exits through a drain line, often with a safety float switch that shuts the system off if the line backs up. Find the drain line (commonly a white PVC pipe near the indoor unit or dripping outside near the foundation) and check for a clog or standing water in the pan. Many systems that 'just stopped cooling' out of nowhere have simply tripped this safety switch.

What each symptom is telling you

If the checks above don't fully explain the problem, the symptom pattern usually points you toward the cause.

When to stop and call a licensed HVAC pro

The checks above are genuinely safe for a homeowner to do — they don't involve opening sealed refrigerant lines, touching high-voltage components, or disassembling the compressor. Past that point, it's a job for a licensed technician with the right tools and training. Call a pro if you notice any of the following:

• Suspected refrigerant (Freon) leak — a hissing sound near the lines, oily residue at fittings, or the coil re-freezes shortly after you thaw it and clear the airflow issue.
• Electrical problems — burning smells, tripped breakers that trip again immediately, buzzing from the outdoor unit, or a system that won't power on at all after you've confirmed the breaker and disconnect are fine.
• A failing compressor or fan motor — loud grinding, humming without the fan spinning, or the outdoor unit's fan is seized or won't start.
• Anything you can't safely reach or aren't sure about — if a fix means removing panels near live electrical connections or handling refrigerant components, that's not a DIY step, regardless of how simple it looks online.

Choosing who to call

If you've worked through the checks above and the system still isn't cooling, the next step is getting a licensed HVAC technician to look at it — ideally without turning it into a multi-quote scavenger hunt while your house sits warm. That's the part we handle: we verify the HVAC company's state license and trade certification, confirm active liability and workers'-comp insurance, and check their review and complaint history for patterns before we ever recommend them to you. You can read more about our vetting standard if you want the details.