TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 1.
Check for voltage (110-120 VAC) across J60A and J60B (Reference Interconnection Diagram, FO-2, Sheet 16) on
the outside of the van. (This heater only works when the pump is shut down and the pump heat switch is on.)
If voltage is not present, go to step 3.
Step 2.
Shut down the ROWPU. Shutdown the generator. Refer to the electrical schematics and interconnect diagrams in
Appendix I. Check the cable to the heater, point-to-point, for continuity or shorts.
(a) If the cable or connectors are defective, replace the cable (para. 4-89).
(b) If the heat lamp is defective, replace the heat lamp (para. 4-89).
Step 3.
Remove connector P15 (Reference Interconnection Diagram FO-2, Sheet 14) from the control panel and check for
voltage across J15J and J15K (Reference Interconnection Diagram FO-2, Sheet 9).
If voltage is not present, notify direct support maintenance.
Step 4.
Shutdown the ROWPU and the generator. Refer to the electrical schematics and interconnect diagrams in
Appendix I. Check for shorts and continuity, point-to-point, from P15J and K to J60A and B, respectively. Open the
distribution pump outside electrical panel. Check MOV Nos. 12 and 13 for physical damage or signs of shorting.
Remove wire Nos. 446 and 447 from the MOV terminals. Use a multimeter and check for continuity from the
terminals which the wires were onto ground.
(a) If a cable or connector is defective, replace/repair the cable or connector (para. 4-27).
(b) Repair any loose or damaged wire in the external electrical panel (para. 4-35).
(c) Replace any damaged wiring harness in the external electrical panel (para. 4-35).
(d) Replace any MOV which is physically damaged or shows continuity to ground from the power terminal
(para. 4-35).
POWER SUPPLY.
Heater power supply does not work when connected to generator batteries (Reference Schematic Diagram FO-1, Sheet 11 schematic
lines 1131-1132).
Step 1.
Check that batteries are charged. The power supply serves only as a junction box during battery power source.
Charge generator batteries.
Step 2.
Disconnect batteries and check cables from battery to van wall and from van wall to power supply for shorts and for
continuity.
Replace any cables that are open or shorted (para. 4-27).
Step 3.
Check cables from power supply to the heaters for shorts and for continuity.
(a) Replace any cables or wires that are open or shorted (paras. 4-27 and 4-60).
(b) If the above checks do not isolate the problem, notify direct support maintenance to check the power supply
cable assemblies for continuity.
2. Heater power supply does not work on AC power (Reference Schematic Diagram FO-1, Sheet 11, schematic line 1129).
Step 1.
Open access panel on the power supply and check for voltages (110-120 VAC) across the incoming leads from the
control panel.
If voltage is present, go to step 4.
Step 2.
Remove connector P17 (Reference Interconnection Diagram FO-2, Sheet 14) from control panel and check for
voltage across J17F and J17G (Reference Interconnection Diagram FO-2, Sheet 9).
If the voltage is not 110-120 VAC, notify direct support maintenance.
Step 3.
Check continuity from P17F to L in the power supply and from P17G to L2 in the power supply.
Replace the cable assembly if open or shorted (para. 4-27).
Step 4.
Check the power supply output for voltage.
If it is not 24-29 VDC, have direct support maintenance check the MOV's for shorts.
Step 5.
Check cables from power supply to the heaters for shorts and for continuity.
Replace any cables or wires that are open or shorted (paras. 4-27 and 4-60).
Change 1 4-41
