TM 9-4940-568-20
2-90
Table 2-11. Air Compressor Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
11. AIR COMPRESSOR WILL NOT START (NO POWER) (CONT).
Check for 208VAC at input of transformer.
If voltage is not present, replace wires #2 and #3 (see schematic Figure 2-6).
If voltage is present, perform next test.
Check for 120VAC at X1 and X2 terminals of transformer.
If voltage is not present, replace transformer (Para 3-2).
If voltage is present, perform next test.
Check for 120VAC at air compressor ON/OFF switch on wire #1.
If voltage is not present, replace wire #1 (see schematic Figure 2-6).
If voltage is present, perform next test.
Check for voltage at output side of ON/OFF switch where wire #7 is connected.
If voltage is not present, replace switch (Para 3-2).
If voltage is present, perform next test.
Check for 120VAC at terminal board terminal #7.
If voltage is not present, replace wire #7 (see schematic Figure 2-6).
If voltage is present, perform next test.
Check for 120VAC on terminal 6 (voltage returning from compressor limit switches and low compressor oil
safety switch).
If no voltage is present, check for voltage going through pressure limit switches. Adjust
pressure settings until compressor turns on and off at desired pressures (Para 11-11). If
compressor will not start, check wiring through low oil switch or replace switches (Para
11-10).
If voltage is present, perform next test.
Check for 120VAC at X1 terminal (wire #6) on air compressor relay.
If no voltage is present, replace wire #6 (see schematic Figure 2-6).
If 120VAC is present, push manual contact close button in center of relay and compressor
should start. If not, replace relay (Para 3-2). If compressor does not start, perform next test.
Disconnect compressor wires at T1, T2, and T3 and reset current sensor and check for 120VAC at T1, T2, and T3.
If no voltage is present, replace current sensor (Para 3-2).
If voltage is present, replace air compressor (Para 11-2).
