Lean a ladder against the exterior wall, and climb up onto the roof, or access the roof through an interior staircase, to reach the rooftop air conditioner, if necessary. Wipe the roof or slab surface around the condenser dry and clean, using a rag. The condenser is the part of the air conditioning unit that sits outside.
Lift up one edge of the air conditioner's condenser unit, or instruct your assistant to do so. Place one anti-vibration pad underneath the raised corner. Lower the condenser edge so that it rests securely on the anti-vibration pad.
Repeat this process on each of the four corners of the condenser.
Push the condenser gently, to make sure it doesn't move and is stable upon the pads. Adjust the condenser edges, if necessary, so that they all sit securely atop the pads.