What Are HVAC Refrigerant Lines?

By Anne Fonda

HVAC refrigerant lines are lengths of copper piping that carry refrigerant from your outdoor air conditioner or heat pump inside to the furnace or air handler during the refrigerant cycle that cools or heats your home.

Depending on the age of your HVAC system, the refrigerant lines may be charged with: 

In a traditional split system, the refrigerant lines are located at the back of the outdoor condenser. They connect to the condenser unit, then go through the exterior wall of your home, and eventually connect to the evaporator coil inside the home (in the furnace or air handler).

If you look at the outdoor unit, you’ll see one thicker line encased in insulation and a thinner copper line with no insulation. The large line carries cool gas refrigerant and is called the suction line, return line, or vapor line. The thinner line carries hot liquid and is called the liquid line or discharge line. 

If you have a basement, you can see the two lines come in through the exterior wall. They may be zip-tied together and connected to exposed beams with brackets until they reach the indoor unit.

In a packaged system, the refrigerant lines are inside the cabinet with the other components.

If the installer sizes the refrigerant piping correctly and installs it properly, your AC or heat pump refrigerant lines should last for the life of the unit or longer, so an average of 20-25 years. If you have a refrigerant leak, the lines may need to be replaced. If you get a new condenser unit, you will have a new refrigerant line set installed at that time.

If you’re not careful, you can accidentally damage your outdoor refrigerant lines. Avoid using garden tools such as a weed whacker, loppers, or shears anywhere near the back of the condenser unit where the refrigerant lines are located. 

Try to keep the area around your outdoor condenser unit clear. Keep flowers, grass, bushes, and other vegetation away from the unit - ideally, several feet away. Hand-pull any vegetation that is obscuring the lines. Mulching around the unit can help keep vegetation from growing into the unit as well.

Repairing or replacing refrigerant lines and recharging the refrigerant is not a DIY job. Reach out to your local American Standard dealer to schedule HVAC repairs.

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need. 

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Alyssa Paulson, Associate Product Manager, Service Parts and Supplies