Cleaned and serviced furnace. Tested flame sensor, pressure switch, hsi, fan motor amperage and capacitor, inducer motor amperage, and gas valve voltage. Cleaned out drain tube to inducer and collector box. Replaced fan motor capacitor due to being extremely low, (MFD 10). Furnace filter was black ( cause of intermittent heating ). Replaced furnace filter that customer provided. (20x20x1). Customer renewed maintenance program. One visit is being used today and will have one visit remaining on plan for spring/ac season. Furnace is from 98. Gave customer estimates for new furnace.