The outdoor unit is humming, the fan inside is running, and the air from the vents is barely cooler than the hallway. It's the most common call we get in Las Vegas, Henderson and Reno from June through September. Here's what's usually behind it, from cheapest to most expensive.
1. Dirty air filter
A clogged filter chokes airflow across the evaporator coil. The coil gets too cold, ices over, and the little air that gets through isn't much cooler. Change it and give the system two hours to thaw before deciding anything else.
2. Thermostat set to “on” instead of “auto”
On the “on” setting the blower runs between cooling cycles, pushing room-temperature air through the vents. Switch to “auto.”
3. Dirty condenser coils
Nevada dust and cottonwood fluff pack the outdoor coil. Heat can't leave the refrigerant, so the system runs long and cools little. This is a big part of a proper AC tune-up.
4. Failed capacitor
The most common electrical failure in desert heat. The outdoor fan or compressor won't start, so the indoor blower moves warm air. A quick, inexpensive fix for our AC repair technicians.
5. Low refrigerant
Refrigerant doesn't get “used up.” If it's low, there's a leak. Ice on the copper line and hissing are the giveaways. A recharge without a leak repair is money down the drain.
6. Frozen evaporator coil
Caused by low airflow or low refrigerant. Turn the system off and let it thaw, then call — running it frozen can kill the compressor.
7. Bad contactor
The relay that sends power to the outdoor unit pits and burns. The unit may click but not run.
8. Leaking or disconnected ductwork
In attics that hit 140°F, a disconnected duct can dump half your cold air into the insulation.
9. Failed compressor
The worst case. A breaker that trips every time the AC starts, or an outdoor unit that hums loudly and shuts down, often means the compressor. Read our guide to AC compressor repair before deciding between repair and replacement.
When it's an emergency
Indoor temperatures above 85°F with infants, seniors or pets at home is not a wait-until-Monday situation. Our 24 hour emergency AC repair line is answered around the clock anywhere in Nevada.