Clean your AC condenser coils
Your outdoor AC unit releases heat through thin metal fins. When dust, grass clippings and cottonwood fluff clog those fins, the AC has to work harder to cool the house. A hose and a can of coil cleaner can help you clear the buildup as part of your spring upkeep. Spray from the inside out if you can get at it. Hosing from the outside tends to push the fluff deeper into the fins.
How the outdoor unit works
The box outside is the condenser. Its sides are covered in rows of thin aluminum fins, and the big fan on top pulls air through them to carry heat away from your house. Anything packed into those fins, like grass clippings, dust or cottonwood fluff, acts like a blanket and makes the whole system work harder.
You're only cleaning the outside of the unit here. The refrigerant lines, electrical parts and fan motor are a technician's job.
What clogs the fins
Mowing and nearby trees coat the fins every season.
Shrubs and tall grass block airflow even when the fins are clean.
Hail, balls and hose blasts flatten fins, which blocks air just like dirt does.
If it's clean and still cools poorly, the system may be low on refrigerant. That means a leak only a technician can fix.
| Situation | Do it yourself? |
|---|---|
| Grass, fluff and dust on the fins | Yes, with this guide |
| A few bent fins | Yes, with a fin comb |
| Large areas crushed flat | Call a technician |
| Ice on the copper lines | Call a technician |
| Oily spots on the coil or lines | Possible refrigerant leak. Call a technician. |
Clean the outdoor unit
- Shut off the powerSet the thermostat to OFF. Then find box on the wall near the unit and pull the block out or flip the switch to OFF.
- Clear around the unitPull weeds and leaves from around the base and trim plants back so there's about 2 feet of open space on every side.
- Brush off loose debrisUse a soft brush or a shop vac with a brush head to lift off fluff and grass from the fins. Brush along the fins, never across them.
- Spray the cleanerSpray foaming coil cleaner evenly over the fins. Let it sit for the time on the can, usually 5 to 10 minutes, while it pushes dirt out.
- Rinse it offRinse with gentle hose pressure, top to bottom, until the foam is gone. Never use a pressure washer, which flattens the fins.
- Straighten bent finsRun a fin comb gently through any bent patches, going with the fins, not across them. Flattened fins block airflow just like dirt does.
- Restore power and check itLet it dry for 30 minutes, put the disconnect back, and set the thermostat to cool. The fan on top should spin, and the air at the vents should feel cool within a few minutes.
Watch it done
- The fins look clean and straight
- The fan on top spins when the unit runs
- Air at the vents feels cool within a few minutes
- About 2 feet of clear space around the unit
If it's clean but still not cooling well
If the air inside still isn't cool, check the indoor air filter next. A clogged filter can cause poor cooling even when the outdoor unit is clean.
If the unit hums but the fan on top isn't turning, shut it off at the disconnect and call for service. The fan motor or capacitor may have failed.
If only one room stays warm, check that room's vents and returns.
What a pro typically charges (a rough estimate; prices vary by area): An AC tune-up, including a professional coil cleaning, typically costs $75–$200.
Find an HVAC technician near you