Before you call for AC repair, four checks take a few minutes and don't need any tools: the thermostat, the air filter, the breaker and the outdoor unit. If all four check out and the house still isn't cooling, the problem is past what's safe to check yourself, and it's time to book a licensed technician.
A "no cool" call usually traces back to one of a handful of causes: something blocking airflow (a dirty filter or a blocked outdoor unit), something electrical (a tripped breaker), a setting problem (the thermostat), or something mechanical inside the system that needs a technician. The first three are worth ruling out yourself, in a few minutes, before you assume the worst.
One thing to keep in mind on an especially hot day: an AC that's simply struggling to keep up with extreme heat, rather than failing outright, can feel the same as a broken one at first. If the house is slowly cooling rather than not cooling at all, give it time before assuming something's wrong, while you work through the checks below.
Start here. Confirm the thermostat is set to "cool," not "off," "heat" or "fan only," and that the set temperature is below the current room temperature so the system is actually calling for cooling. A smart or programmable thermostat can also be on a schedule that's working against you — check that a vacation or "away" mode isn't holding the temperature up.
If the thermostat itself seems to be misreading the room, or the house feels cool but clammy, that's a job for thermostats and indoor air rather than something to troubleshoot further on your own.
A clogged filter restricts airflow, which can make a perfectly working AC seem broken — weak airflow, a system that runs constantly, or ice forming on the indoor coil. The Department of Energy and ENERGY STAR both put the replacement interval during cooling season at roughly every one to two months. If you can't remember the last time you changed it, that's a good sign it's due.
Check your electrical panel for a tripped breaker or a blown fuse serving the AC. The Department of Energy's own guidance is specific here: "check fuses or circuit breakers. Let the unit cool for five minutes before resetting."
Walk outside and look at the condenser unit. Leaves, grass clippings, mulch and overgrown foliage pressed against it block the airflow it needs to release heat. The Department of Energy recommends trimming foliage back at least two feet from the unit, and both DOE and ENERGY STAR recommend keeping the area around it clear generally. Clear off any obvious debris resting against the unit itself, but don't open the unit's housing.
Everything past these four checks belongs to a licensed HVAC technician, and one part of it is federal law, not just good sense: only an EPA Section 608–certified technician may recharge refrigerant or do any work that opens a refrigerant circuit. The EPA states it plainly: "Section 608 Certification is required to recharge appliances. Refrigerant for stationary appliances is only sold to certified technicians or the companies that employ them." It's illegal to knowingly vent refrigerant while servicing AC equipment, whether it's an older refrigerant or a newer one like R-410A.
That federal rule sits alongside Virginia's own licensing: doing HVAC work for pay in Virginia also needs a DPOR tradesman license, or the supervision of someone who holds one.
A low refrigerant charge, a failing compressor, or wiring issues beyond a single breaker reset are all signs the Department of Energy's own advice ends the same way: "hire a professional technician." There's no homeowner step past that point — not testing the charge, not opening the unit, not attempting a repair.
| Check | What to do | Safe for a homeowner? |
|---|---|---|
| Thermostat | Confirm it's set to cool and calling for the AC | Yes |
| Air filter | Replace if it's been more than 1–2 months | Yes |
| Breaker | Let the unit cool 5 minutes, reset once | Yes, once |
| Outdoor unit | Clear leaves, clippings and foliage at least 2 ft back | Yes |
| Refrigerant charge | — | No — EPA-certified technician only |
| Compressor or internal wiring | — | No — licensed technician only |
If the four checks above don't bring the AC back, or the breaker trips again after one reset, stop troubleshooting and book a technician. Regular seasonal service also catches a lot of this before it turns into a no-cool afternoon — see when to service your AC in Virginia for the timing.
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This is general information, not legal advice. For refrigerant and equipment rules, see the EPA's Section 608 program.
Last updated September 2026.
Yes, once. The Department of Energy's guidance is to let the unit cool for about five minutes before resetting the breaker. If it trips again right away, stop resetting it and call a professional instead — a breaker that keeps tripping is telling you something beyond a one-time overload.
No. Under federal law (the Clean Air Act, 40 CFR Part 82), only an EPA Section 608–certified technician may recharge refrigerant or do any work that opens the refrigerant circuit. Refrigerant for stationary equipment like a home AC is sold only to certified technicians or the companies that employ them.
Roughly every one to two months during the cooling season, according to both the Department of Energy and ENERGY STAR. A dirty filter restricts airflow and can make a working AC seem like it's failing.
If the thermostat, filter, breaker and outdoor unit all check out and it's still not cooling, the problem is likely something that needs a licensed technician to diagnose — refrigerant, the compressor or internal wiring aren't homeowner checks. Book service rather than keep troubleshooting.