How to clean an air conditioner

Cleaning your air conditioner will extend its working life and help you to avoid inconveniences such as bad smells and unhygienic air quality. If you’re ever unsure about cleaning your air conditioner, of course you should contact a reputable air conditioning expert who offers air conditioner cleaning and services. If you’re looking to ‘DIY’, however, here are a few pointers.

What you will need:

  • Screwdriver
  • Vacuum cleaner
  • Water
  • Bleach
  • A pipe cleaner

Cleaning the indoor AC blower unit:

  • Switch the blower off at the control panel.
  • Start by replacing the old air filter with a new one. Consult the owner’s manual to obtain the correct size, or if you’re going to an air conditioning parts supplier, take your old filter with you and ask an assistant.
  • Open the blower compartment and vacuum up any visible dust and debris. If your AC has lubrication ports here, squeeze up to 5 drops of AC formulated oil into the ports. Do not use all-purpose oils such as WD-40. If you are unsure, check the owner’s manual.
  • Remove the plastic condensation tube and check for algae growth. If the tube is clogged, either replace it or soak it in a solution that is 20 parts water to 1 part bleach and then refit the tube.
  • Use a pipe cleaner to clean the drain tube.
  • Place the drain tube back onto its port.
  • Restart the AC unit.

Cleaning the outdoor AC unit:

  • Shut off the power. Either use the shut off box, mains or fuse box to guarantee no power is flowing through the unit.
  • Use a vacuum with a soft bristle brush attachment to vacuum the condenser fins. You may have to unscrew a metal plate to access the fins. Check for grass and weeds that are trapped in the fins and brush out any debris. The fins are delicate so be careful not to damage them. If you find any fins are bent, it is very simple to straighten them using a dinner knife or similar.
  • Unscrew and remove the grille on top of the air conditioner. It is likely that a fan will lift out with the grille, so be prepared to support it from below. Wipe the fan clean using a damp cloth.
  • Using a cloth or a hosepipe and moderate water pressure, clean the vents of the unit from the inside out.
  • Reassemble the unit.
  • Go indoors and turn your thermostat from ‘Cool’ to ‘Off’ or ‘Power down’.
  • Leave your air conditioner for 24 hours.
  • Restart the air conditioner and set the thermostat to ‘Cool’ and your desired temperature, then wait for ten minutes.
  • Check that your central air conditioning system is working by checking the pipes connecting the outdoor unit to the home. One should feel cold to the touch while the other should feel warm. If this is not the case, you will require professional help to check the coolant levels. If the the pipes are as described above, you air conditioner is working perfectly and good to go.


Following these steps should improve the efficiency and reliability of your air conditioner, too. So, it’s always worth knowing how to clean your air conditioner, inside and out.

FM Mechanical Ltd Ltd is proud to supply air conditioning units and services nationwide from our base in Sheffield, South Yorkshire. Our team of expert engineers are on hand to carry out air conditioning services, where we will check and maintain your unit so that it will perform its best for years to come. For any more information about our products and services, be sure to get in touch with a member of our team who will be happy to talk about your individual requirements.