How Can I Make My AC Colder?

Short answerTurning the thermostat lower won't make it cool faster, says American Standard. Help the system instead: replace a dirty filter, clear 2 feet around the outdoor unit, close blinds, keep lamps and TVs away from the thermostat, and run a fan. If the air still isn't cold, we recommend an HVAC technician check the refrigerant and coils.

Why a lower setting doesn't help

American Standard says a central AC or heat pump only cools as fast as the system allows. It says a lower setting wastes energy and strains your system.

What you can do today

Replace a dirty filter. DOE says a clogged one reduces the unit's ability to cool the air.
Clear the outdoor unit. Bryant says to keep at least 2 feet of clearance and gently rinse dirty fins.
Close blinds and cut indoor heat sources, also from Bryant.
Keep lamps and TVs away from the thermostat, DOE says.
Set the fan to Auto, Bryant says.
Use a ceiling fan. DOE says it lets you raise the thermostat about 4 degrees without feeling warmer.

What makes a bigger difference over time

DOE points to insulating your attic and walls, sealing cracks and openings, and sealing ducts. It says air loss through ducts accounts for about 30 percent of a cooling system's energy use. Ask a contractor to check your ducts if rooms cool unevenly.

When it's not you, it's the system

If you've done all that and the air still isn't cold, DOE lists low or leaking refrigerant, worn controls and duct problems as jobs for a professional. We don't recommend refrigerant as a do-it-yourself job.

AC Not Cooling? What to Check Before You Call

Common questions

What temperature should I set it to?

DOE notes that running at 78 degrees instead of 72 can save 6 to 18 percent on your cooling bill. American Standard suggests staying within 20 degrees of the outdoor temperature. Comfort is your call.

Will a bigger AC cool better?

We wouldn't assume so. We recommend asking an HVAC contractor to do a sizing check rather than guessing.