TM 5-4120-377-14f. During periods of very cold weather the fabric cover should be rolled down and snapped.NOTEFresh (outside) air cannot be introduced with fabric cover rolled down. Close damper.AIR CONDITIONERCOVER (FABRIC)TS4120-377-14/2-14Figure 2-14.Fabric CoverNOTEAn overheat thermostat located near the heating elements will turn them off if thetemperature in the heater compartment reaches an excessive level.2-18