On a hot afternoon, an air conditioner that runs but blows warm air is one of the most common calls we get. Sometimes the fix is something you can do in a minute. Sometimes it's a part that needs a technician. Here's how to tell the difference.
1. Check the thermostat
Make sure it's set to Cool, not Heat, Auto or Fan, and that the set temperature is a few degrees below the room. If the fan is set to On instead of Auto, it keeps blowing between cooling cycles, and that air will feel warm. If the screen is blank, replace the batteries.
2. Check the air filter
A clogged filter chokes the airflow across the indoor coil. The system works harder, cools less, and in bad cases the coil freezes. Pull the filter and hold it up to a light: if you can't see through it, replace it.
3. Check that the outdoor unit is running
Go outside while the system is calling for cooling. You should hear the outdoor unit's fan and compressor running. If the indoor fan is blowing but the outdoor unit is silent, the house is just circulating its own warm air.
- Check the breaker for the outdoor unit in your electrical panel. If it has tripped, you can reset it once. If it trips again, leave it off and call: a breaker that keeps tripping is protecting something.
- Make sure nothing is blocking the outdoor unit: plants, a cover, leaves or debris against the coil.
4. Look for ice
Ice on the copper lines at the outdoor unit, or on the indoor coil, means the system can't move heat properly. Turn cooling off and set the fan to On to let it thaw. Running it frozen can damage the compressor. Ice usually points to low airflow (often the filter) or low refrigerant, and low refrigerant means a leak that a technician needs to find.
5. Look for water
Water around the indoor unit, or a system that has shut itself off, can mean the condensate drain is blocked. Many systems have a safety switch that stops cooling when the drain backs up.
When to call a technician
- The breaker trips again after one reset
- The outdoor unit hums or clicks but the fan doesn't spin
- Ice comes back after you've thawed the system and changed the filter
- You smell burning or see scorch marks
- The air is still warm after all of the checks above
Please don't open electrical panels on the equipment or try to add refrigerant yourself. Both are jobs for a licensed technician.
If you've been through the list and it's still blowing warm, call us at 805-965-6326 or send us a message. Our NATE-certified technicians will find the cause before recommending a fix.