Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
Continuity and short circuit test arrangements for compressor motor are shown in
Figures 4-1 and 4-2.
Ensure that all circuit breakers are set before troubleshooting.
1. Air compressor wont start (Reference Schematic Diagram FO-1, Sheet 8, schematic lines 824-629 -control
circuits, Reference Schematic Diagram FO-1, Sheet 5, schematic lines 518-521 - power circuits).
Shut down the ROWPU. Open the control panel. Check that the overload reset button on MS1 is in by
(a) If the reset button is in, go to step 2.
(b) If the button is out and wont reset, notify direct support maintenance to replace the overload
heaters on MS1 (Reference Interconnection Diagram FO-2, Sheet 10) and then go to steep 4.
(c) If the reset button is out but resets when pushed, notify direct support maintenance to adjust
the door reset assembly for MS1 and then go to step 4.
Refer to the operators manual and power up the control panel. Observe MS1 when the air compres-
sor start switch is turned on. Be sure the system air pressure is below 1400 psig (9653 kPa) before
turning on the air compressor. The indicating plunger should go in and stay in which indicates the
control circuits are working properly.
(a) If the indicating lunger goes in and stays in, go to step 4.
(b) If it does not pull in, or, if it pulls in but does not stay in, notify direct support maintenance to
troubleshoot the air compressor circuits.
Disconnect PI 1 from the control panel and check for continuity across PI1 C and PI1 C (Reference
Interconnection Diagram FO-2, Sheet 14). It should read zero.
If it does not read zero, notify direct support maintenance to troubleshoot the air compressor pres-
Shut down the generator. Refer to the electrical schematic Appx. I-1 and interconnect diagram Appx.
I-2. Set ohmmeter to Ohms x 1000 scale. Check each lead, 1T1, 1T2, and 1T3 from the outlet side of
MS1to ground. The reading should be infinity for each lead.
If the meter reading is zero there is a short circuit, go to step 6.
Set the multimeter to the Ohms x 1 scale and check for continuity between all pairs of leads; 1T1 and
1T2,1T2 and 1T3, 1T1 and 1T3. Readings should be zero or near zero for each step.
If the checks performed in both steps 4 and 5 are okay , return the ROWPU to operatbn.
Check connectors J/P20, J/P65, and J/P67, (Reference Interconnection Diagram FO-2, Sheet 16)
for hose pins and for signs of arcing.
Replace any connector or cable that shows damage (pare. 4-27 and 4-79).
Check continuty, point-to- piont, from P20A to J67A, P20B to J67B, P20C to J67C, and P20H to
J67D. Check each lead for shorts between phases and shorts to the ground wire. The reading should
be infinity for each check.
(a) Replace any cable or connector that shows open during continuity checks (pares. 4-27 and
(b) Replace an cable or connector that shows a short between phases or a short to ground
paras.4-27 and 4-76).
epair any hose or damaged wires in the pump skid junction box (para. 4-76).
(d) Replace any MOVS (Reference Interconnection Diagram FO-2, Sheet 16) in the pump skid
junction box that show physical damage or are shorted to ground from the power terminal
Tag and disconnect motor leads (T1, T2, T3). Set multimeter to Ohms x 1000 scale and connect test
leads between each motor lead and the motor frame. Readings should be infinity for each step.
Replace motor if the meter reading is zero (para. 4-79).