AC Not Working? Try These Fixes Before You Call (Save Yourself $$$)

Your AC has stopped cooling, or it's running but not keeping up. Your first instinct is to call a technician—and sometimes that's the right move. But before you do, here are some quick checks you can do yourself that might solve the problem entirely or at least give us useful information when you call. Many of these take 5 minutes and could save you a service call fee.

1. Check Your Thermostat

Start here. Seriously.

• Is the thermostat set to COOL mode? Check right now. You'd be shocked how often someone accidentally has it set to OFF or HEAT.

• Is the temperature setting LOWER than the current room temperature? If you want 72°F and it's 78°F, the system needs to run. If it's already 71°F and you set it to 72°F, it won't kick on.

• Are the batteries dead? Most thermostats run on batteries. If the display is blank or dim, replace them. Dead batteries = no signal to the AC unit.

• Is the thermostat getting power? If it's a digital display, it should show something. If it's completely dark, you've got a power issue.

Try this: Set the thermostat to 68°F to force the system to run. If it fires up, your problem might just be settings. If it still doesn't run, move to the next check.

2. Check Your Circuit Breaker

If your system isn't getting power, it won't run.

• Locate your electrical panel in your garage, basement, or utility closet.

• Look for a breaker labeled AC, HVAC, or with an amperage rating (usually 30–60 amps) — it should be different from standard breakers.

• Is it in the OFF or TRIPPED position? (A tripped breaker will be in the middle or clearly off.)

• Flip it all the way OFF, then back ON. This resets it.

• If it trips again immediately, you've got an electrical problem — don't keep flipping it. Call a technician or electrician.

If the breaker stays on and you're still not getting cooling, your power is getting to the panel but something else is wrong. Move to the next check.

3. Check Your Air Filter

A clogged air filter is the #1 reason systems underperform or shut down.

• Locate your return air filter — usually in a closet, basement, hallway, or attic. It's a big box with a slot or access panel.

• Pull out the filter and hold it up to a light. Can you see light through it?

• If it's dark, gray, or you can barely see light, it's clogged. Replace it. Filters are $10–$30 and take 30 seconds to swap.

• Use the size printed on the old filter (usually 16x25x1, 20x25x1, etc.) to buy the right replacement.

This alone fixes a shocking number of complaints. A clogged filter starves your system of air, forces it to work harder, can cause freezing, and triggers shutdowns.

4. Check Your Return Air Vents

Your AC needs air to cool. If the returns are blocked, the system starves.

• Find the return air grills/vents in your home (usually in hallways, closets, or on walls/ceilings).

• Is anything blocking them? Furniture, curtains, closed doors, boxes, toys, clothes?

• Clear the area in front of returns — at least 12 inches should be open.

• Make sure interior doors (especially bedroom doors) aren't staying closed all day — closed doors restrict airflow and create pressure problems.

If returns are clear and you're still not cooling, move on.

5. Check Your Outdoor AC Unit

Your outdoor condenser unit needs to work for your system to work.

• Go outside and look at the unit. Is it running? You should hear/feel the fan spinning and compressor running.

• Is there leaves, grass, dirt, or debris piled around it? Clear it away. Your unit needs air circulation around all sides—at least 2 feet of clearance.

• Is there ice on the indoor coil visible through the indoor unit? Ice means airflow or refrigerant problems—don't ignore this, call a tech.

• Listen for the compressor. You should hear a humming or buzzing sound. If there's total silence, power isn't reaching it or the compressor isn't running.

Pro tip: If the outdoor unit's fan isn't spinning but the compressor is running, the fan motor might be bad. If neither is running, check your breaker again.

6. Make Sure Exterior Doors and Windows Are Closed

This sounds obvious, but people are surprised by this one.

• Garage door open? Letting hot air in constantly.

• Back door or patio door left open? Same problem.

• Windows open for fresh air? Close them while you're trying to cool. You can't outrun the heat gain.

Close everything and give the system 30 minutes to catch up. If your home has been soaking up heat, it takes time to cool down.

7. Check for an AC Disconnect Switch

Some systems have a disconnect switch (looks like a pull-out block or lever) near the outdoor unit or on the wall nearby.

• Is it in the OFF position? Pull it to ON.

• Is there a wall-mounted switch near the unit marked AC or COOL? Make sure it's switched on.

This is rare but happens.

8. Listen and Feel

Use your senses.

• Do you feel cold air coming from the vents inside? Put your hand over an air vent. Cold air means the system is actually cooling. If the air is warm or room temperature, something's wrong.

• Can you hear the outdoor unit running? If there's total silence, power or a component isn't working.

• Is the system running constantly but not cooling? That's different from not running at all. This usually points to refrigerant, sizing, or airflow issues.

9. Check Your Thermostat Location

Where your thermostat is placed affects what it reads.

• Is it in direct sunlight? Sunlight on the thermostat makes it think the house is hotter than it actually is, causing it to shut off early.

• Is it next to a heat source? (Register, lamp, etc.) Move it or cover direct sun with a blind.

• Is it in the right spot? Ideally, it's in a central hallway away from vents, doors, and windows.

10. Write Down What You've Found

Before you call a technician, jot down what you've checked:

• Thermostat mode and setting

• Breaker status

• Filter condition

• Whether the outdoor unit is running

• Whether you feel cold air at vents

• What sounds the system is making

• How long it's been running without reaching set temperature

When you call with this info, the technician already knows the basics are covered, can give you better guidance, and can prep for what they need to bring. Sometimes they can even solve it over the phone.

When to Just Call a Technician

If you've checked everything above and:

• The system still isn't running at all

• Ice is visible on the indoor unit

• The outdoor unit isn't running

• You feel warm air instead of cold air from the vents

• The system runs constantly but never reaches temperature

• You hear strange noises (grinding, banging, hissing)

...it's time to call. You've narrowed down the problem and saved yourself from a wild-goose-chase diagnosis.

Bottom Line

Most of the time, the fix is simple: change the filter, clear the vents, close a door, or reset the thermostat. These quick checks take 10–15 minutes and could save you $150–$300 on a service call. Even if they don't fix the problem, you'll have useful information for the technician, and they can focus on the real issue instead of diagnosing basics.

We're always happy to help if you need us—but we're also happy if you save some money by catching something simple first.