TM 5-4520-256-14
3-8. TROUBLESHOOTING. (Refer to Table 3-2).
Table 3-2. Unit Troubleshooting
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1.
CENTRIFUGAL FAN FAILS TO OPERATE.
WARNING
Be careful when working with live electrical circuits to prevent contacting electrical voltages
which could cause death or serious injury. Personnel should stand on "High voltage",
switchboard matting (Federal Specification ZZ-M-81A), 3/16 inch (4.8 mm) or greater, to avoid
being grounded.
Step 1.
Check for 120 (+/-10) Vac, 50/60 Hz, 20/25 fused circuit breaker protected electrical power is available at
shelter electrical receptacle.
If 120 (+/-10) Vac is not present, troubleshoot and repair shelter electrical system.
If 120 (+/-10) Vac is present, proceed to step 2.
Step 2.
Check for 120 (+/-10) Vac at TBI, terminals 1 and 2.
If voltage is not present at TB1, terminals 1 and 2, replace power cable (para 3-29).
If voltage is present and proper, proceed to step 3.
Step 3.
Check for 120 (+/-10) Vac between TB1 terminal 1 and terminal 1 of circuit breaker (CB1) after resetting
the circuit breaker.
If voltage is not present (indicating circuit breaker controls are still open) replace circuit breaker (CB1) (para 3-
19).
If voltage is present and proper, proceed to step 4.
Step 4.
Check for 120 (+/-10) Vac between terminal 5 and terminal 6 of OFF/VENT/HEAT switch (S1), with switch
in VENT position.
If voltage is present (indicating open contacts), replace selector switch S1 (para 3-14).
If voltage is not present proceed to step 5.
3-6
