TM 10-3930-669-20 16-12.  HEATER VENT REPLACEMENT. This task covers: a.  Removal b.  Installation INITIAL SETUP Tools and Special Tools Tool Kit, General Mechanic's: Automotive (Item 1, Appendix B) Equipment Condition Engine OFF (TM 10-3930-669-10) Parking brake applied (TM 10-3930-669-10) Wheels chocked (TM 10-3930-669-10) Cab door open (TM 10-3930-669-10) a.  Removal. NOTE All heater vents are removed the same way.  Left rear heater vent is shown. (1) Pry heater vent (1) from heater vent frame (2). (2) Remove four screws (3) and heater vent frame (2) from cab heater housing (4). 16-40