TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1.
Media filter inlet valve does not open (system normal). MEDIA FILTER INLET valve light off (Reference
Schematic Diagram FO1, Sheet 7, schematic line 715).
Step 1. Check valve for actual position.
(a)
If valve is closed, go to step 2.
(b)
If valve is open, refer to valve light does not show correct valve position troubleshooting (malfunction
3).
Step 2. Disconnect the valve electrical connector P39. Check for 110-120 VAC across pins J39D and J39E
(Reference Interconnection Diagram FO-2, Sheet 15). If there is voltage present, notify direct support
maintenance.
CAUTION
Even after closing the block valve in the next step there will be 85 psig (586 kPa) air in the tubing to the
automatic valve. Be careful when disconnecting the tubing at the block valve. Slowly back off the tubing
nut to allow air pressure drainage.
Step 3. Close the air block valve at the air manifold for the media filter inlet valve. Disconnect the air tubing to
the valve actuator. Check if the valve stem retracts into the actuator.
(a)
If the stem retracts, repair the valve actuator by replacing the air control relay and solenoid valve
(para. 4-47).
(b)
If the stem does not retract or if it retracts with a jerky motion, replace the actuator (para. 4-47).
Change 7 4-51
