When your air conditioning stops working on a hot day, it's tempting to immediately call for help. But before you reach for the phone, there are several simple troubleshooting steps you can try that might save you time and money.
Step 1: Check the Thermostat
It sounds simple, but thermostat issues account for a surprising number of "broken AC" calls. Before anything else:
- 1. Ensure the thermostat is set to "Cool" mode, not "Heat" or "Off"
- 2. Set the temperature at least 5 degrees below the current room temperature
- 3. Check that the fan setting is on "Auto" rather than "On"
- 4. Replace the batteries if it's a battery-powered thermostat
- 5. Ensure the display is working and showing the correct temperature
If your thermostat is programmable, make sure the schedule hasn't been accidentally changed. Sometimes a power outage can reset the programming.
Step 2: Inspect the Air Filter
A clogged air filter is one of the most common causes of AC problems. A dirty filter restricts airflow, which can cause the system to overheat and shut down.
How to Check Your Air Filter
- → Locate the filter (usually behind the return air vent or in the furnace)
- → Pull it out and hold it up to light
- → If you can't see light through it, it needs replacement
- → Replace with the same size and type (check the old filter for dimensions)
- → Cost: $5-$20 for a standard filter
Most filters should be changed every 1-3 months, depending on your environment and whether you have pets.
Step 3: Check the Circuit Breaker
If your AC unit isn't turning on at all, it may have tripped a circuit breaker. Air conditioners require significant electrical power and can sometimes overload circuits.
Circuit Breaker Steps
- 1. Locate your electrical panel (breaker box)
- 2. Look for any breakers in the "middle" position (not fully on or off)
- 3. Flip the AC breaker fully to "Off" first, then back to "On"
- 4. If it trips again immediately, don't keep resetting it - call a professional
- 5. Check if there's a separate breaker box near the outdoor unit
Note: If the breaker trips repeatedly, this indicates a serious electrical issue that requires professional attention. Do not continue resetting it.
Step 4: Inspect the Outdoor Unit
The outdoor condenser unit can accumulate debris that prevents proper operation. A quick inspection and cleaning can often resolve issues.
Outdoor Unit Checklist
- ✓ Remove any debris (leaves, grass, dirt) from around the unit
- ✓ Ensure at least 2 feet of clearance around the unit
- ✓ Gently rinse the condenser coils with a garden hose (no pressure washer)
- ✓ Check that the unit is level (use a level tool)
- ✓ Listen for unusual noises when it runs
- ✓ Make sure the disconnect switch near the unit is in the "On" position
Step 5: Check for Ice on the Unit
Ice buildup on the evaporator coils or refrigerant lines is a common issue that can stop your AC from cooling. If you see ice:
- 1. Turn off the AC and let it thaw for 24 hours with the fan running
- 2. Check the air filter again - ice is often caused by restricted airflow
- 3. Ensure all vents are open and unobstructed
- 4. If ice returns after thawing, you may have a refrigerant leak - call a pro
Running the AC with ice on the coils can damage the compressor, which is one of the most expensive components to replace.
When to Call a Professional
If none of the above steps resolve the issue, or if you encounter any of these situations, it's time to call an HVAC professional:
Burning smell from the unit
Shut off the system immediately and call for emergency service.
Loud screeching or grinding noises
Mechanical components may be failing and could cause further damage.
Unit won't turn on after checking breaker
Electrical issues require professional diagnosis.
Refrigerant leak suspected
Refrigerant handling requires EPA certification - it's not a DIY job.
Common AC Problems and Costs
Here's what to expect if you do need professional AC repair in 2026:
Typical AC Repair Costs
- Refrigerant recharge$150 - $400
- Capacitor replacement$100 - $250
- Contactor replacement$150 - $350
- Fan motor replacement$300 - $600
- Compressor replacement$1,500 - $3,000
- Evaporator coil replacement$1,000 - $2,500
AC Prevention Tips
Preventive maintenance can avoid most AC emergencies and extend the life of your system:
Monthly Tasks
- ✓ Check and replace air filter
- ✓ Clear debris from outdoor unit
- ✓ Test thermostat operation
Annual Tasks
- ✓ Professional tune-up ($100-$200)
- ✓ Clean evaporator coils
- ✓ Check refrigerant levels
- ✓ Inspect ductwork for leaks
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