Condensation that forms on your outdoor A/C lines reduces efficiency and raises your energy costs. So you need to install new insulation. Start by peeling off all the old foam insulation.. Then measure the outside diameter on the larger of the two tubes (the skinny tube doesn’t need insulation). Unfortunately, you won’t find the right insulation at any home center. Instead, contact a refrigeration supply house or online supplier for new foam and insulating tape (Insul-Lock tubing insulating foam, and Nomaco Poly Tape, both from pexsupply.com).
Measure the length of the A/C line and cut the insulation a few inches longer. Leave the adhesive liner in place and install the insulation.