Short answer
Set the thermostat to "Off" and switch the disconnect box by the outdoor unit to "Off". Clear leaves, grass and branches about two feet around it. Rinse the fins from the top down with a garden hose on a gentle setting, never a pressure washer. Let it drip a few minutes, then turn the power back on. Do it every spring, and again in summer if trees shed on it.
Safety first
Always switch the disconnect box to "Off" before you clean the unit, and never open its electrical panels. Do not use a pressure washer or household chemicals on the fins.
How to clean the outdoor AC unit
1Leaves and dirt on the outdoor unit
The fins on the sides let the unit shed heat. Clogged with dirt, leaves or grass, it works harder and cools less.
Read all the steps
- Leaves and dirt on the outdoor unit. The fins on the sides let the unit shed heat. Clogged with dirt, leaves or grass, it works harder and cools less.
- Power off: thermostat and disconnect. Set the thermostat to "Off". Then switch the disconnect box by the unit to "Off" so the fan cannot start while you work.
- Clear two feet around the unit. Sweep away leaves, pull weeds and trim grass and bushes. Lift sticks off the top grille. Do not reach inside the fan.
- Rinse gently, top down. Use a garden hose on a gentle setting and spray down along the fins. No pressure washer or stiff brush: the fins bend easily.
- Power back on. Let it drip a few minutes. Switch the disconnect back on and set the thermostat to "Cool".
- Still not fixed? Call an HVAC contractor Especially if: many fins are bent flat or the coil looks crushed.
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What not to do
- Do not use a pressure washer, a stiff brush or a screwdriver on the fins. They bend and block the airflow.
- Do not open the electrical panels or lift off the top with the fan attached. That is a job for a technician.
- Do not use household chemicals. If the coil needs more than water, use a cleaner made for AC coils and follow the label, or ask a technician.
- Do not stack things on the unit or let bushes grow against it.
How often to clean it
Clean it once a year, in spring, before the heavy cooling season. Check it again in summer if you have trees, cottonwood, a dusty yard or a dryer vent nearby. A yearly tune-up by a technician includes a deeper coil cleaning.
When to call an HVAC technician
- Many fins are bent flat or the coil looks crushed.
- The coil is still caked with dirt after a gentle rinse.
- The fan does not spin when you turn the power back on.
- You see oily spots on the coil or the lines (a possible refrigerant leak).
Frequently asked questions
Can I hose down my outdoor AC unit?
Yes, with the power off at the disconnect box. Use a garden hose on a gentle setting and spray from the top down along the fins. The unit is built to sit in the rain.
Can I use a pressure washer on my AC unit?
No. The pressure bends the thin fins and can push dirt deeper into the coil. A garden hose on a gentle setting is enough.
How often should I clean my AC condenser?
At least once a year, in spring. Check it again during the summer if leaves, grass clippings or cottonwood collect on it.
Do I need to turn off the power to clean my AC unit?
Yes. Set the thermostat to "Off" and switch the disconnect box by the unit to "Off" so the fan cannot start while you work.
Can I use a coil cleaner on my AC?
You can use a cleaner made for AC condenser coils and follow its label. Never use household chemicals, and never mix products.
How much space does my outdoor AC unit need?
Keep about two feet clear on all sides and the space above it open, unless the manual says otherwise. Bushes, fences and stored things too close choke the airflow.