TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
11. Backwash outlet valve will not open (system backwash position), BACKWASH OUTLET valve light off (Refer-
ence Schematic Diagram FO-1, Sheet 7, schematic line 712).
Step 1. Check valve for actual position. Refer to ‘AUTOMATIC VALVES” general note.
If valve is open, refer to valve light does not show correct valve position troubleshooting (malfunc-
tion 14).
Step 2. Disconnect the valve electrical connector P38. Check for 110-120 VAC across pins J38D and J38E
(Reference Interconnection Diagram FO-2, Sheet 15).
It there is voltage present, notify direct support maintenance.
CAUTION
Even after closing the blockvalve in the next step there will be85 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 blockvalve at the air manifold for the backwash outlet valve. Disconnect the airtubing 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).
12. Backwash outlet valve will not close (system normal). Valve light on (Reference Schematic Diagram FO-1,
Sheet 7, schematic line 712).
-
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Check valve for actual position. Refer to ‘(AUTOMATIC VALVES” general note.
If valve is closed, refer to valve light does not show correct valve position troubleshooting (malfunc-
tion 14).
Disconnect the valve electrical connector J38. Check for11O-120 VAC across J36D and J38E.
(a) If voltage is not present, go to step 6.
(b) If voltage is present, go to step 3.
Reconnect J38 and check for 110-120 VAC across terminals 4 and 5 on the valve.
If no voltage is present at the terminals, replace the valve cable and connector (para. 4-47).
CAUTION
Even after closing the block valve in the next step there will be85 psig (586 kPa) air in
the tubing to the automatic valve. Slowly back off the tubing nut at the block valve to
relieve air pressure before removing the air tubing at the automatic valve.
Close the air block valve at the air manifold for the backwash outlet valve. Remove the air tubing from
the automatic valve and check that air is being supplied to the valve by opening the air block valve.
If air does not come out the tubing with the air block valve open, find the blockage in the air tubing
and repair or replace it (para. 4-24 and 4-68).
Check the wiring on the valve for damage or looseness.
(a) Repair any damage to the wiring (para. 4-47).
(b) If the wiring is okay, replace the air control relay and solenoid valve (para. 4-47).
Remove connector P14 (Reference Interconnection Diagram FO-2, Sheet 15) from the control panel
and check for 110-120 VAC across J14J and J14K.
(a) If voltage is not present, notify direct support maintenance.
(b) If voltage is present, go to step 7.
Power off. Check for continuity from P14J to J38D and from P14K to J38E.
Replace the cable and connectors if faulty (para. 4-27).
13. Backwash outlet valve will not close (system clean). Valve light on (schematic line 712).
Refer to the same problem in system “NORMAL” (malfunction 12).
4-56
Change 1
