How to Clean a Condenser


The air conditioner in your home (whether it’s a simple HVAC System or a reversible heat pump for the winter) has an indoor evaporation unit for pulling heat out of the air and an outdoor condenser unit for releasing that heat to the outdoors.  The outdoor unit (typically a large grill-like box with a fan in the center) is what releases heat.  To do this, refrigerant, compressed to be a higher temperature than the surrounding air, is forced through the grill of fins along the walls of the box.  It’s a good idea to make sure that this grill is clean each spring.  Much of this can be done yourself, or you can hire a professional to perform a full HVAC service!

Clearing and Washing

The very first thing you want to do is to clean out the area immediately around the condenser unit.  You need at least two to three feet of clearance around the condenser for air to flow properly.  The condenser works by moving air through the fins to remove heat from the refrigerant.  Shrubbery, debris, or yard equipment that’s stacked too close to the condenser will block airflow, preventing the condenser from operating properly.

The next step is to cut power to the unit.  You never want to work on actively powered equipment, so turn off power at the breaker.  Once this is done, remove the grill around the condenser unit.

Use a pressure washer to clear dirt, debris, and buildup from the fins of the condenser.  Be very careful as the fins are fragile and do bend easily.  Spray the power washer direct at the fins, if you hit them from the side they may bend.  Don’t be worried if a few fins bend while washing, it can happen and you’ll fix those next.

If the pressure washer is having difficulty clearing some of the fins, consider using a coil and condenser cleaning solution.  Be careful though, these cleaners are highly caustic.  They should never be used in an enclosed space and you should always follow the directions exactly as listed. Once the condenser fins are completely clean, you’re ready to move to the next step.

Straightening Fins

The last step is to straighten out the fins of the condenser.  When the fins bend, it reduces the surface area available for airflow to move through the grill.  Since maximizing airflow is essential to maintaining efficient heat exchange, it’s important to keep them straight.

A condenser fin comb is fairly inexpensive.  They come in a few different styles and sizes but the tool is roughly the same every time: a sturdy plastic comb where the tines fit between the fin blades on the condenser.  To use it effectively, start at the bottom, with the handle facing upward and pull the straightener to the top of the condenser.  Holding the comb this way ensures that the handle won’t prevent you from reaching the base of the condenser unit.

Once you’ve straightened out the fins, restore the protective grill over the fins and the turn the power back on.  Now your system is ready for use once again.

  1. Clear the area around the condenser (give 2 to 3 feet of clearance)
  2. Turn off power
  3. Remove the protective grill
  4. Use a power washer or cleaning solution to clean the condenser fins
  5. Use a fin comb to straighten out the fins
  6. Restore the protective grill
  7. Turn the power back on

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