Step 4 · Run Refrigerant Lines and Electrical Wiring

Drill a hole through the exterior wall for the refrigerant lines and electrical conduit. Feed the copper refrigerant lines (suction line and liquid line) and the low-voltage control wiring from the outdoor unit location to the indoor unit location. Ensure the lines are properly insulated to prevent energy loss and condensation. Use a conduit to protect the wiring and refrigerant lines where they pass through the wall. Connect the control wiring to the appropriate terminals on both units according to the wiring diagrams.