How do I Install an Air Conditioner Liquid Line Dryer?

Moisture and contaminants wreak havoc on any type of air conditioning or refrigeration system. They are usually introduced to the system through improper servicing of the unit. The liquid line dryer is located between the condenser and the expansion device. The purpose of the dryer is to trap particles and moisture. If any particles or moisture reach the expansion device, they will accumulate and restrict the refrigerant flow. Another problem is that when they mix with the oil an acid is formed which eats away the compressor windings as well as other parts of the unit. The dryer might be a flared or a sweat (soldered) connection.

Moisture and contaminants are enemies of air condioners.
  1. Recover the refrigerant with a recovery machine. The method of recovery depends on the particular type of machine you are using. The proper method will be described in the manufacturer's instructions and usually on the machine itself.

  2. Remove the old dryer if one is present. If it is a flared type, use a wrench on the flared nut and another wrench on the dryer. If it is a sweat fitting, make sure your manifold gauge is open because the pressure in the system will increase as heat builds up.

  3. Replace the dryer, or if there is not one, cut the liquid line between the condenser and expansion device with a tubing cutter. It will usually be a sweat fitting. The size of the dryer will be dictated by the size of the copper tubing as well as the size of the unit.

  4. Add nitrogen to the unit through the manifold gauges and leak check the fittings. If no leaks are indicated, release the nitrogen and pull a vacuum with the vacuum pump. After pulling a proper vacuum, charge and check the unit for proper operation.


  • When working on an electrical device, turn the power off and tag it with a note so it is not inadvertently turned on.

About the Author

Karleigh Spears has a B.A. in journalism and graduated from San Jose State University. She has written for the Hendersonville Star News and loved it. It was very dramatic and a great experience.