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How to Flush the A/C System

by Baptist Johnson

Air conditioning repairs can be expensive. Technicians might charge hundreds of dollars to troubleshoot and service an A/C system. Before spending money on professional services, try to flush your vehicle’s A/C system yourself. The procedure for flushing the A/C system is fairly straightforward. You need a few automotive tools and about two hours.

1

Park your vehicle in a safe location on even ground. Engage the parking brake, but allow the engine to idle. Turn on the air conditioning system. Open the hood.

2

Locate the air conditioning service fittings. The low-side fitting is located on the refrigerant hose that goes from the accumulator to the compressor. The high-side fitting is located on the refrigerant hose that goes from the compressor to the condenser. Remove the plastic caps on the service fittings.

3

Connect the blue hose on the manifold gauges to the low-side fitting. Connect the red hose on the manifold gauges to the high-side fitting. Attach the yellow hose on the manifold gauge to the vacuum pump. Open the valves on the hoses and activate the vacuum pump. Allow the vacuum to evacuate the A/C system until the pressure reading on the manifold gauges reach 0 psi. Turn off the vacuum pump. Disconnect the hoses from the A/C service fittings. Turn off the ignition.

4

Disconnect the low-side and high-side refrigerant hose from the condenser using an adjustable wrench. Pour the flush solvent into the high-side inlet of the condenser. Apply compressed air into the high-side inlet of the condenser. Catch flush solvent with a dense rag as it comes out of the outlet hole in the condenser. Look for visible dirt and grime mixed in with the solvent. Continue to flush the condenser until all debris is removed.

5

Follow the low-side refrigerant hose from the compressor until you reach the accumulator, which is mounted near the rear firewall. Unscrew the mounting bracket that secures the accumulator to the firewall. Set aside the mounting bolts in a safe place.

6

Remove the accumulator using the adjustable wrench. Look inside the low-side refrigerant hose where you disconnected the accumulator. Locate the orifice tube. Remove the orifice tube from the refrigerant hose using needle-nose pliers. Inspect the orifice tube for visible debris or obvious signs of damage. Replace the tube, if necessary.

7

Replace the accumulator with a new one. Secure the accumulator to the mounting bracket using a wrench and the mounting bolts you previously removed. Secure the mounting bracket back to the firewall. Reconnect the refrigerant hoses to the condenser.

8

Disconnect the vacuum pump from the yellow hose of the manifold gauge. Attach a can of refrigerant to the yellow hose. Turn on the ignition. Turn on the air conditioning system. Turn the A/C settings to maximum. Open the pressure valve on the yellow hose from the manifold gauge. Open the pressure valve on the blue hose as well.

9

Allow the A/C system to recharge to its recommended range. Close the pressure valve on the blue hose when the reading reaches between 25 and 40 psi. Disconnect the manifold gauges from the services fittings. Replace the plastic cap onto the service fittings. Allow your A/C to run for at least 10 minutes to circulate the refrigerant.

Tip

  • Consult a professional when purchasing a replacement accumulator.

Warning

  • Consult a professional if your vehicle was manufactured before 1994 as it might use R-12 Freon refrigerant, which is a substance regulated by the Environmental Protection Agency.

Items you will need

About the Author

Baptist Johnson was first published in 2000 when a poem he wrote won first prize in a local writing contest. He also writes and edits for Etched Press Society, a micro-publishing company based in Wilmington, N.C. Johnson has a Bachelor of Science in business administration from East Carolina University.

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