TM 9-4120-357-14
NOTE
Before you use this table, be sure you have performed all applicable operating checks.
TABLE 4-2. TROUBLESHOOTING
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1. AIR CONDITIONER FAILS TO OPERATE.
WARNING
Hearing protection must be worn when maintenance is performed while air condi-
tioner is in operation. Failure to heed this warning can result in hearing loss or in-
jury.
Step 1. Check to be sure that main power cable is connected.
Connect cable.
Step 2. Check mode selector switch for correct setting.
Turn selector switch to COOL.
Step 3. Verify that circuit breaker has not tripped.
Pull then push the circuit breaker reset knob.
Step 4. Make sure that you are using 208-volt, 50/60-cycle, 3-phase current.
Check each phase of supply line with voltmeter.
Step 5. Inspect main power receptacle connector for breakage.
Replace broken connector.
Step 6. Check for loose electrical connections.
Tighten connections.
Step 7. Verify that high- and low-pressure cutout switches have not opened.
Press reset buttons on high- and low-pressure cut out switches.
WARNING
Disconnect power from the air conditioner before doing maintenance work on the
electrical system. The voltage used can be lethal.
Step 8. Check continuity of fuses XF1 and XF2.
Replace bad fuses.
Step 9. Check transformer: 208-volt primary, 30-volt secondary.
Replace bad transformer.
Step 10. Check filter-rectifier assembly by applying 35+ 3-volt ac to input terminals, and observing
voltmeter attached to (+) and (-) terminals. Voltmeter should read 24-28 volts, dc.
Replace bad filter-rectifier assembly.
4-8
