Clean your AC condenser coils
The outdoor half of your air conditioner works by pushing heat out through thin metal fins. When those fins are packed with dust, grass clippings and cottonwood fluff, the heat has nowhere to go. The AC runs longer, cools less and costs more. Cleaning them is an easy spring job with a hose and a can of coil cleaner.
What's actually going on
The outdoor unit is called the condenser. Its sides are wrapped in a coil covered in rows of thin aluminum fins, and a big fan on top pulls air through them. Anything blocking those fins works like a blanket over the unit.
You're only cleaning the outside here. Refrigerant lines, electrical parts and the fan motor are for a technician.
Why it happens
The most common cause of a condenser that can't breathe. Mowing and trees load it up 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 the disconnect 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 and straightenRinse with gentle hose pressure, top to bottom. Comb any bent fins straight, let it dry for 30 minutes, then restore power.
Still not fixed?
If the air inside still isn't cool, check the indoor air filter next. A clogged filter causes more cooling trouble than anything else.
Hear the unit running but the fan on top isn't turning? Shut it off and call for service. The motor or capacitor may have failed.
What a pro charges: An AC tune-up, including a professional coil cleaning, typically costs $75–$200.
Common questions
How often should I clean my AC condenser coils?
Once a year, in spring. More often if you have cottonwood trees, lots of dust, or a dog that sheds near the unit.
Can I use a pressure washer on my AC unit?
No. It bends the fins flat and can push water into the electrical parts. A regular garden hose is plenty.
Can I just use water to clean AC coils?
A hose rinse helps. A foaming coil cleaner lifts grime that water alone leaves behind.
Should I cover my AC unit in winter?
Cover only the top, if anything, to keep leaves out. Fully wrapping it traps moisture and invites rodents.