Performed preventative maintenance for heat pump system. This was an air conditioning maintenance for a heat pump system. Replaced the customer supplied air filter (20x20x1). Inspected all the electrical components. Confirmed proper high and low voltages. Tested the temperature split between the supply and return. System is operating at a 20° differential at a current temperature of 70°. Inspected the gravity drain for any blockage. Found some debris in the drain and was able to pick it out of the clean out tee. Tested the amp draw of the blower, compressor and fan motor. All were operating within the manufacturer specs. The pipe the customer had concerns about is a partially rusted supply duct. This is partially rusted due to the water shut off valve for the outdoor hose hook up. The packing nut on the valve just needs to be tightened. I also found a water regulator with a minor leak. Let customer know to call his water company for repair/replacement of the regulator since it’s on the