Super tune up performed today on a propane furnace with straight cool condenser installed in 2013. Blower wheel and evaporator coil are dirty and need to be cleaned. All electrical connections are tight with no corrosion. All amp draws are within spec. Refrigerant levels show as low but is most likely due to improper airflow across the coil due to it being dirty. Outdoor unit was washed and waxed. Need to return for rec work later this week. Customer is available after noon every day.