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How to Clean an A/C Window Unit

While Universal often blogs about HVAC central air systems, we are well aware that many people in the Houston area still have an A/C window unit (or single room air conditioner). These units remain a popular choice for older homes, garages and apartments where installing a duct system would be cost prohibitive or architecturally difficult. Even with a small A/C unit, it’s imperative that it be cleaned and serviced annually (just like a central air system) to ensure maximum efficiency. One of the recurring problems with window units is that the evaporator and condenser coils, or the cooling fins, will get blocked or bent.

Any blockage can restrict airflow, cause freezing and keep the air from cooling. The inactivity throughout the winter season also leaves the unit susceptible to mold and mildew, so it’s imperative to clean it every spring. This process is fairly easy, though it will take two people and require a fin comb (if you don’t already own one). A professional cleaning would cost over $100, so this project will save you money – and help ensure your unit runs efficiently all summer.


  • Work Gloves
  • Shop-Vac
  • Rags
  • A/C Coil Cleanser
  • Electric Motor Oil
  • All-Purpose Cleaner
  • Screwdriver


  • Before you begin, make sure that you disconnect the A/C window unit from its power source. Either unplug the cord or, if it’s wired directly, turn off the circuit breaker.
  • Wash the outside cover and window area with a wet cloth. This will keep the excess dirt and grime from getting into the unit once it is removed.
  • Remove the cover; some slide off easily while others might need to be unscrewed/unhinged.
  • You will need two people to remove the unit. First, the trim panel (or plastic filter holder) will need to be removed. Most can be easily snapped off. Once the panel has been removed, gently detach the unit from the window (or slide it out of the wall). Make sure that you have a secure place for the unit to land – close to the window/wall.
  • An A/C window unit will also require the removal of the mounting frame and case. While the designs vary, the case screws can usually be found along the bottom edge.


  • Look over the cooling fins along the back of the unit. Grab your fin comb and gently straighten any bent fins. Using the tool is easy. Simply match the end of comb to the fin spacing on the coils. Insert the comb and pull up to straighten the dents. Refer to the directions on the package of the comb if there are questions on proper procedure.
  • Using a shop-vac, vacuum all of the dirt and grime from the coils.
  • Spray the coils with a can of air conditioner foaming coil cleanser. Most cleaners are made for use with any type of A/C unit – and are self-rinsing. An inexpensive can of cleaner can be found for under $6 at Home Dept.
  • While the foam cleans the coils, move to the fan blades and wash them off with a rag and a simple counter cleaner.
  • Does the fan motor have oiling ports? If so, remove them and drop some electric motor oil into them.
  • The air filter is one of the most important components to the unit. Make sure that you replace it (or thoroughly wash it if it’s a reusable design).
  • After it is dry, return and secure the unit to its position and replace the cover.
  • Return the power and review the performance. If it’s not running at high efficiency, contact an HVAC professional to have it serviced.

5 Tips for Preventing Window AC Mold

Remember that Universal is the premier home services company in Houston and can assist you with all your HVAC needs. If you have an A/C window unit (or single room unit) that isn’t performing properly – or needs its annual tune-up, we can help! Call us today at (713) 364-0226 to schedule an appointment today!