Safety controls; temperature and pressure controls, ect
belt tension; refrigerant charge; superheat; fan RPM; water chemical feed and feed rate; burner fuel/air ratios; gas pressure; set point of controls and limits; compressor cylinder unloaders; damper close-off; sump floats, etc.
belt drives; drive couplings; air fins, etc.
motors; fan and damper bearings; valve stems; damper linkages; fan vane linkages, etc.
electrical connections; mounting bolts; pipe clamps; refrigerant piping fittings; damper sections, etc.
coil surfaces; fan impellers and blades; electrical contacts; burner orifices; passages and nozzles;pilot and igniter; cooling tower baffles, basin, sump and float; chiller condenser and boiler tubes, etc.