Cummins/Onan — Bilge Blower Does Not Operate When Load Is Connected

Testing & diagnosis · Bilge Blower Circuit

From a Cummins/Onan service manual covering: 15.0 HA, 15.0HA-23/24D, 15.0HA-23/25D, 7.5 HA, 7.5HA-21/24D, 7.5HA-21/25D, 7.5HA-23/24D, 7.5HA-23/25D. Check it applies to your exact model before use.

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Procedure

1. Check switch positions. Auto-Manual switch S1 should be at Auto position, and bilge blower controls at proper automatic start position.
2. Battery terminals may be incorrect. Should have negative ground only.
3. Check that cranking limiter relay K3 is at reset position. Depress pushbutton to reset.
4. Check 6-1/4 ampere fuse. If open, check for short circuit. Remedy and replace fuse.
5. Place Auto-Manual switch S1 to Manual position. Check fuse on load sensor printed circuit board and replace if open. Make sure incoming wires from generator aren't connected to the load side of the co
6. With a hydrometer, check battery specific gravity.
7. Check load circuits. Disconnect load wires from control and substitute another load (such as a 100-watt lamp).
8. Reconnect battery cables and check for battery voltage at control TB1-B+ terminal. Place Auto-Manual switch S1 to Auto position. If generator set starts with this load, check for problem in load circu
9. Jumper a wire from terminal TB1-B+ to terminal TB1-5. If bilge blower does not operate, problem is in bilge blower or its circuitry.
10. If bilge blower operates, perform checks A-D: A. Check security of wiring connections between switch S1 and relay K1 terminal 30. B. Check for battery voltage at relay K9 terminal 8. If voltage is abs

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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