ARMY TM 9-4120-380-14
AIR FORCE TO 35E9-136-21
4.29 PRIME UNIT SELECT SWITCH (S11). This task covers inspection, testing, removal and installation
Tool kit, service, refrigeration unit (Item 1, Appendix B)
Disconnect input power to the air conditioner before performing any internal
maintenance. Voltages used can KILL Shutting the unit off at the control panel does not
disconnect unit power.
(1) Disconnect air conditioner input power at source; and
a. Check that wire leads are properly connected (see fig. FO-2.)
b. Check that leads are not loose or broken. Tighten loose leads Replace if defective
Check switch (3) for signs of overheating or other visible damage. If wires are damaged, replace as necessary
a. Using multimeter, check continuity between center and outer terminals with wire connected. Set switch to
PRIMARY, then BACKUP.
b. If switch fails test, replace switch
a. Tag and disconnect leads.
b. Remove nut (1), washer (2), and switch (3) from panel.