How to Flush a HVAC Suction Line

Disconnect both ends of the suction line from the system. If the lines are already disconnected in preparation for mechanism replacement, do not reconnect them until you have finished the flushing procedure. Lingering residue in the lines can contaminate the new equipment if it is connected before being cleaned. Choose one end of the line as the exit point for the flushing fluid.

Crimp the line near the exit point to restrict, but not completely stop, the flow of liquids through it. You can close the line with a crimping tool, or simply bend it at a sharp angle with a pair of pliers. Blasting the line with nitrogen before crimping can increase the efficiency of the flushing procedure, according to Contracting Business. This optional step may be necessary if there is loose debris or a complete physical blockage in the line.

Connect the canister containing the flushing agent to the suction line. Some flushing products may come with an adaptable connector, but you may have to purchase or create one that forms a sealed connection between the flushing agent and the line. There are several legal flushing agents on the market. Check the legality of each chemical solution in your state and other legal jurisdictions before using them.

Release the flushing agent into the line as directed. The amount required depends on the flushing agent, the dimensions of the line and level of contamination. It may take several hours to clean heavily contaminated lines. Blast the line with nitrogen again after you finish flushing it with the cleaning agent.