A heating or cooling failure is an emergency when it puts someone at risk or threatens the house — no cooling with infants, older adults or medically vulnerable people in the home during a heat wave; no heat when indoor temperatures are dropping toward the 50s or when pipes could freeze; any gas smell, carbon-monoxide alarm, burning smell or electrical smoke; or active water damage from a leaking system — and it’s a next-morning call in almost every other case, including a healthy household with a dead AC on a warm night. Here’s how to decide in a minute, and what to do either way.
Call now if
Someone in the house is an infant, over about 65, pregnant, or has heart, lung or other conditions affected by heat or cold, and the house is above roughly 85°F or below the low 60s and moving the wrong way. You smell gas: leave the house, don’t flip switches, and call the gas utility’s emergency line first, then a contractor. A carbon monoxide detector sounds: leave and call 911 or the gas utility. Burning smell, smoke, scorched wiring or a breaker that trips repeatedly. Water is actively leaking onto a ceiling, floor or electrical equipment (AC leaking water). Outdoor temperatures are forecast well below freezing and you have no heat, which risks pipes.
Can wait until morning if
The household is healthy adults; the house is uncomfortable but not dangerous; the outdoor unit hums or won’t start, the air is warm, or the system is short-cycling; the thermostat is blank; or the system froze up and needs to thaw anyway. In these cases you’ll pay less and get the same technician by booking the first slot tomorrow.
What to do right now, either way
Do the ten-minute checks: thermostat mode and batteries, filter, breakers and disconnect, outdoor unit running and clear, and look for ice (AC not cooling). If you see ice, set the system to Off and the fan to On. If a breaker tripped, reset it once only. Then keep the house tolerable: temporary fixes while you wait covers cooling and heating a house without a working system, and what not to do (no unvented gas heaters, no charcoal or generators indoors, no space heaters on extension cords).
What after-hours service costs
Expect a higher diagnostic fee ($150–$300 is typical after hours versus $75–$200 in business hours) and 25–50% more on labor, plus parts. Many companies quote a flat emergency call fee. If the fix is a capacitor or contactor, tonight’s total might be $300–$600; if it’s a compressor or a leak, the technician will likely stabilise the system and return in daylight anyway, so the emergency premium buys you a diagnosis, not a repair. 24-hour HVAC service: what to expect.
Finding someone tonight
Each city page on the North Carolina registry marks contractors who run 24/7 service and shows the license status we found, so you can pick a licensed one at 11pm rather than the first name that answers.