Properly Performed spring inspection on whole home system. Checked the filter, checked blower wheels for built up dirt/dust, cleaned flame sensors, cleared inducer ports, tested hot surface igniters, took delta Ts, tested safety switches, tested all electrical components, tightened all electrical connections, took running volts/amps, monitored systems operations. Bad blower capacitor Improper flu pipe Dirty air ducts Microbial growth in plenums Dirty condenser coil Rusty outdoor unit.