"A typical maintenance check-up should include the following. Check thermostat settings to ensure the cooling and heating system keeps you comfortable when you are home and saves energy while you are away. Tighten all electrical connections and measure voltage and current on motors. Faulty electrical connections can cause unsafe operation of your system and reduce the life of major components. Lubricate all moving parts. Parts that lack lubrication cause friction in motors and increase the amount of electricity you use. Check and inspect the condensate drain in your central air conditioner, furnace and/or heat pump (when in cooling mode). A plugged drain can cause water damage in the house and affect indoor humidity levels. Check controls of the system to ensure proper and safe operation. Check the starting cycle of the equipment to assure the system starts, operates, and shuts off properly. "