TM 9-4520-258-14
4-27.
AIR PRESSURE SWITCH - continued.
e.
Adjustment (Refer to Figure 4-42)
(1)
Disconnect power cable (1) from power source.
(2)
Remove air return duct (2) from the unit.
(3)
Open rear side door (3).
(4)
If testing indicated air switch was closed, proceed as follows:
(a)
Remove cover (4) from air switch (5), loosen locknut (6).
(b)
Turn adjustment screw (7) clockwise/in until meter indicates infinity. Turn adjustment screws (7) one
quarter turn more.
(c)
Tighten locknut (6), install cover (4), and proceed to step (12).
(5)
If testing indicated air switch was open, proceed to step (6).
(6)
Remove cover (4) from air switch (5), loosen locknut (6) and turn adjustment screw (7) one half turn
counter clockwise/out.
(7)
Close rear side door (3).
WARNING
Electrical high voltage cannot be seen, but it can kill you. Electricity is unlike most other
dangerous things you can come in contact with because it gives no warning and no symptoms
to be wary of. Its effect is immediate. It can kill you, render you unconscious, or severely burn
you. To ensure your safety and that of other maintenance personnel, always observe the
following precautions: BE CERTAIN that there is someone assisting you who can remove power
immediately.
FOR ARTIFICIAL RESPIRATION, REFER TO FM 21-11.
(8)
Connect power cable (1) to power source.
(9)
Turn MODE SWITCH (8) to the VENT position and observe meter indication.
(a)
If the air switch (5) closes the meter will indicate continuity, turn MODE SWITCH (8) to OFF and
proceed to step (10).
(b)
If the air switch (5) does not close the meter will indicate infinity. Repeat steps (1), (2), (3), (6), (7),
(8) and (9).
(c)
If the air switch (5) does not close after turning the adjustment screw (7) completely clockwise/in
replace the air switch.
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