When your AC starts blowing warm air on a 95-degree Northern Utah afternoon, you want answers fast. Some causes are simple things you can fix in a few minutes. Others need a technician. Here’s what to check, in order.
1. Check the thermostat settings
It sounds obvious, but it happens all the time:
- Make sure it’s set to Cool, not Heat or Off.
- Set the fan to Auto, not On. With the fan set to On, air blows constantly, even when the AC isn’t cooling, so it can feel like warm air between cycles.
- Set the temperature a few degrees below the current room temperature.
- Replace the batteries if your thermostat uses them.
2. Check the breakers
Central air systems usually have two breakers in your electrical panel: one for the indoor furnace or air handler and one for the outdoor unit. If the outdoor breaker has tripped, the fan inside keeps blowing but nothing gets cooled.
Reset a tripped breaker once. If it trips again, leave it off and call for service, because that points to an electrical problem.
There’s also a disconnect box on the wall next to the outdoor unit. Make sure it hasn’t been switched off or pulled.
3. Check the air filter
A dirty filter chokes airflow. That makes the AC work harder, cool poorly, and in some cases freeze up. Replace it if it looks gray or clogged.
4. Look at the outdoor unit
Go outside while the AC is supposed to be running:
- Is the fan on top spinning? If you hear humming but the fan isn’t moving, the capacitor or fan motor may have failed. This is one of the most common summer repairs. Don’t poke anything into the unit.
- Is the unit covered in cottonwood fluff, grass clippings, or leaves? A blocked coil can’t release heat. Turn the power off at the disconnect, then gently rinse the fins from the inside out with a garden hose. Keep shrubs trimmed about two feet back.
5. Look for ice
Check the copper refrigerant lines at the outdoor unit and the indoor coil, if you can see it. Ice or frost means something is wrong, usually low airflow or low refrigerant.
Turn the AC off and run just the fan for a few hours to melt the ice. Running a frozen system can damage the compressor. If it freezes again after you’ve replaced the filter, call for service.
6. Check the condensate drain
Many systems have a safety float switch that shuts the AC off if the condensate drain backs up. If you see water in the drain pan under the indoor coil, or a small switch on the drain line, a clog may be the cause.
When it’s time to call a technician
Call for service if:
- The breaker trips again after you reset it
- The outdoor fan isn’t spinning, or the unit hums or clicks without starting
- The lines freeze again after you’ve replaced the filter
- You hear grinding, squealing, or banging
- Everything looks normal, but the air still isn’t cool
Low refrigerant isn’t a do-it-yourself fix. An air conditioner doesn’t use up refrigerant, so low refrigerant means there’s a leak that needs to be found and repaired.
Need a hand?
Elevate Heating and Air repairs air conditioners throughout Ogden, Layton, Roy, and Northern Utah. Tell us what you’ve already checked when you call. It helps us figure out the problem faster.
