TM 5-4520-256-14
3-14.
OFF/VENT/HEAT SWITCH (SI) MAINTENANCE-Continued.
b.
Inspection.
(1)
Inspect switch for broken or burned terminals.
(2)
Inspect switch for bent or broken switch. Be sure that switch has positive action in all positions.
(3)
Inspect switch housing for cracks.
c.
Cleaning.
WARNING
Cleaning solvent, Federal specification P-D-680, is toxic and flammable. Use only in a well-
ventilated area. Avoid prolonged breathing of fumes. Keep solvent away from flames. Do not
use in excessive amounts. Avoid skin contact.
(1)
Wash the switch in cleaning solvent (item 11, Appendix E).
(2)
Allow to dry completely.
d.
Testing.
(1)
Connect multimeter between terminals 1 and 2.
(2)
Rotate switch to VENT position. Meter should indicate > 10 ohms.
(3)
Rotate switch to OFF position. Meter should indicate < 1 Meg-ohms.
(4)
Connect multimeter between terminals 1 and 3.
(5)
Rotate switch to HEAT position. Meter should indicate > 10 ohms.
(6)
Rotate switch to OFF position. Meter should indicate < 1 Meg-ohms.
(7)
Connect multimeter between terminals 5 and 6.
(8)
Rotate switch to VENT position. Meter should indicate > 10 ohms.
(9)
Rotate switch to OFF position. Meter should indicate < 1 Meg-ohms.
(10)
Connect multimeter between terminals 5 and 7.
(11)
-Rotate switch to HEAT position. Meter should indicate > 10 ohms.
(12)
Rotate switch to OFF position. Meter should indicate < 1 Meg-ohms.
(13)
Connect multimeter between terminals 9 and 11.
(14)
Rotate switch to HEAT position. Meter should indicate < 10 ohms.
Change 3 3-32
