Remove Rust And Debris From An Outdoor Condenser Unit

If the outdoor condenser unit that is connected to your home's air conditioning system hasn't been used in a long time and has visible rust spots on its surface and debris trapped inside of its cover, clean it with the following steps. After finishing, the unit will be more likely to operate efficiently when you turn the air conditioning on in your house.


  • screwdriver
  • foam brush
  • naval jelly
  • scouring pad
  • bucket of soapy water
  • handheld scrub brush
  • water hose
  • shop vacuum cleaner
  • plastic sheeting
  • rust inhibitor

Remove The Rust

Turn off the air conditioning system. Go outdoors and inspect the unit's cover. Some models have screws holding them in place, while others do not contain hardware and can be lifted off immediately. Once the cover has been removed, locate all of the rust spots on the unit's interior. Use a foam brush to apply an even coat of naval jelly to each one. Apply a coat of naval jelly to any rust spots on the unit's cover as well.

The jelly will dissolve the rust after it has penetrated the spots for several minutes. Once the rust begins dissolving, rub the rust spots with a scouring pad to assist with removing it.

Clean The Interior And The Cover And Apply A Rust Inhibitor

Use soapy water and a scrub brush to clean the condenser unit's interior and its cover. Afterwards, rinse both parts off with a strong stream of water and wait for them to dry. Use a shop vacuum cleaner's hose to suck up any debris that is stuck in between small parts that make up the unit's interior or in the cover's vents.

Protect the unit's interior and cover from rusting in the future by applying a rust inhibitor to each one. Many rust inhibitors come in spray form. Place a couple pieces of plastic sheeting around the condenser unit to protect the ground from the inhibitor. Lay the cover on top of another piece of sheeting. Apply an even coat of the inhibitor to the unit's interior and one side of the cover. Wait for the inhibitor to dry. Once this occurs, flip the cover over and apply the inhibitor to the other side. After the inhibitor dries, reattach the unit's cover. 

The condenser unit will work properly whenever you would like to turn the air conditioning on in your home. Clean the unit occasionally to prevent debris from getting stuck between crevices. The rust inhibitor will last for several years. If you ever notice rust forming on the unit's surface again, you will need to add a new coat. Use resources like to learn more