Customer has 23 y/o Ruud system that operates for whole house. System was not heating due to door switch not being engaged. Secured door switch. Replaced 16x25x1 filter. Noticed during inspection that run capacitor is bad. Blower wheel cleaning needed. No water protection present. Drain line in poor condition. Flue venting is incorrect. Burners are rusted. Evaporator coil is rusted. Condenser electrical components are poor. Condenser coils in poor condition. System is R22 based. Recommend system replacement.