Cummins/Onan — UFRO Adjustments
Adjustments · Voltage regulator (AVR) under-frequency roll-off
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DFAA, Cummins/Onan DFAB, Cummins/Onan DFAC, Cummins/Onan DFBF, Cummins/Onan DFCB, Cummins/Onan DFCC, Cummins/Onan DFCE, Cummins/Onan DFE
Before you start
- Use an insulated handle screw driver to prevent electrical shock.
Procedure
- Make a note of the no-load frequency.
- Determine roll-off frequency by turning the governor speed pot until the LED lights; if okay go to step 5.
- Adjust the governor speed pot to the proper roll-off frequency.
- Turn the UFRO pot until LED goes off, then slowly turn it back until the LED just goes on.
- Adjust the governor speed pot back to the initial frequency setting.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Typically 59 Hz for 60 Hz applications and 49 Hz for 50 Hz applications.
Full service-parts list: Cummins/Onan DFBF →, Cummins/Onan DFCC →, Cummins/Onan DFCE →, Cummins/Onan DFE →
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.