Tear out air handler and hanging kit replace new hanging kit new air handler new drain pan attached to hanging kit hook up existing plenums drain line after flushing copper after flushing, high voltage and low voltage flow switches and line and pan. Change new thermostat tear out old condenser replace new condenser on new pad, tiedown four corners Tyanne copper after the flush nitrogen test copper 400 psi vacuum down to 500 µm hook up high-voltage low-voltage and drain line start up everything running factory, specs, checking and cool and heat mode