Carrier HVAC Unit 48TFF012

Shut off unit power supply and install lockout tag

Loosen belt by loosening fan motor mounting plate nuts

Loosen movable pulley flange setscrew

Adjust movable flange to change fan speed

Set movable flange at nearest flat of pulley hub and tighten setscrew

Shut off unit power supply and tag disconnect

Adjust fan height as shown in Fig. 48

Shut off power to unit and tag disconnect

Slide out burner section side panel

Disconnect gas piping at unit gas valve

Remove wires connected to gas valve and mark each wire

Remove wires from ignitor and sensor wires at the Integrated Gas Unit Controller (IGC)

Remove the 2 screws that attach the burner rack to the vestibule plate

Slide the burner tray out of the unit

Reinstall the gas train by reversing the procedure

Remove burner rack from unit as described in Removal and Replacement of Gas Train section

Remove burners from rack if dirty

Clean burners and cross-over port using a soft brush

Adjust spark gap according to Fig. 54

Reinstall burner rack as described in Removal and Replacement of Gas Train section

Remove evaporator coil access panel

If economizer is installed, remove economizer by disconnecting Molex plug and removing economizer mounting screws

Clean coil using a commercial coil cleaner or dishwasher detergent in a pressurized spray canister

Wash both sides of coil and flush with clean water

Backflush toward return-air section to remove foreign material

Ensure not to overflow the evaporator drain condensate pan

Flush condensate pan after completion