TM 9-4520-258-14
Section V. UNIT TROUBLESHOOTING PROCEDURES
4-9. INTRODUCTION.
This section provides troubleshooting information for the ASH unit at the unit level of maintenance. It consists of the
malfunction index, listing the most common malfunctions, and the troubleshooting table, Table 4-2. The troubleshooting
table is presented as flow diagrams for each malfunction listed in the malfunction index. Each diagram provides the
procedure and corrective actions to return the ASH unit to operational readiness. The ASH Electrical Schematic, FO-1,
and Wiring Diagram, FO-3, are provided to assist during troubleshooting.
4-10. TROUBLESHOOTING.
The troubleshooting table lists the common malfunctions which can occur in operation of the ASH unit. The tests,
inspections and corrective actions should be performed in the order given.
MALFUNCTION INDEX
MALFUNCTION
PAGE
1.
Unit Will Not Start................................................................................................
4-28
2.
Combustor Fan Does Not Operate.......................................................................
4-31
3.
Fuel Pressure Stays at 25 PSI or Less in HEAT AUTO or HEAT MANUAL ..........
4-33
4.
Unit Flames Out Repeatedly (more than 3 times in a row) ...................................
4-34
5.
No Fuel Pressure Indicated..................................................................................
4-35
6.
Low Fuel Pressure Indicated................................................................................
4-37
7.
Excessive Black Smoke in Exhaust .....................................................................
4-38
8.
Fan Motor Slows Down, Indicator Lights Dim .......................................................
4-39
9.
Improper/No Spark in Igniter................................................................................
4-40
10.
Unit Backfires or Rumbles in AUTO and/or MANUAL HEAT modes.....................
4-43
11.
Combustor Fan Does Not Operate
(Black exhaust smoke and loud rumble) ..............................................................
4-44
12.
No Combustion in HEAT AUTO Mode .................................................................
4-46
13.
No Combustion in HEAT MANUAL Mode.............................................................
4-52
4-26
