How to Flush an Air Conditioning System

If a vehicle's air conditioning system is not operating correctly, sometimes flushing the entire system will improve its efficiency. Flushing the air conditioner means removing any oil, dirt or other contaminants. Systems can be flushed at an auto repair clinic or can be done at home with the right equipment. Make sure to research the proper procedures for the make and model of the vehicle before starting any flushing process.

Flushing a car air conditioner could help it work more efficiently.
  1. Turn the vehicle off and lift the hood. Connect the manifold pressure gauge to the high and low valves. Connect the hose to the reclaimer. Press the "On" button on the reclaimer, opening both valves slowly.
  2. Press the "Vacuum" button on the reclaimer once the first cycle is complete. The reclaimer will vacuum the air conditioner for about 15 minutes, eliminating any moisture in the system and removing any remaining refrigerant oil.
  3. Unscrew the lines leading to the condenser with a wrench. These will be short, small lines. Detach the low lines on the side that are near both the accumulator and the evaporator.
  4. Pinch the electrical switch connector on the accumulator and remove the switch. Unscrew the bracket that holds the accumulator to the firewall, removing it and the orifice tube entirely. The tube is inside the line and will need to be removed with pliers. Replace the tube if any dirt is found inside.
  5. Add the air conditioner flush liquid into the reclaimer bottle. Close the lid tightly. Make sure the reclaimer is pressurized to about 100psi of air pressure. Push the flushing liquid through with a flushing gun that is attached to the cylinder. Repeat the same steps on all of the system parts, with the exception of the compressor. Continue flushing the air conditioner until no dirt or oil is evident. Use aerosol flush as an alternative to liquid flush if no flushing gun is available.
  6. Reassemble the air conditioner, replacing all O-rings and the orifice tube. Install the accumulator. Make sure all lines are screwed tightly.
  7. Add refrigerant after tightening all of the lines leading into and out of the condenser. Most vehicles use R-134a refrigerant to recharge the system. This can be purchased from department or auto parts stores.
  8. Connect the low and high lines to the reclaimer and connect the other ends to one of the valves. Open the valves on the air conditioner and the pressure gauge. Press "Vacuum" on the reclaimer and "Enter." Press "Vacuum" a second time, which will vacuum the air out of the chamber.
  9. Research the proper charge for the air conditioning system. The information should be in the owner's manual or underneath the vehicle's hood. Select the "Charge" option on the reclaimer and enter the numbers for the charge. Press "Enter" when finished. Open the valve slowly and push the "Charge" button.
  10. Close the valves and remove the lines from the reclaimer once the air conditioner has been charged. Place the red and blue caps on the appropriate valves.

Things You Will Need

  • Freon refrigerant
  • Coolant pressure gauge


  • Wear gloves and eye protection when flushing the air conditioning system.
  • Do not flush the compressor, accumulator, receiver drier, expansion valve or any portion of the muffler that is between the condenser and air conditioner compressor. If these areas have clogs, they will most likely need to be replaced.
  • Do not use flush solutions that are oil based. Use solutions that are approved for air conditioning systems

Photo Credits

  • Klimaanlage pkw image by crossgolfing from Fotolia.com