ServiceNomad RV · Knowledge
WFCO Converter Failure Symptoms
WFCO power converters are extremely common in RVs built in the 2000s-2010s, and when they fail, they often take multiple systems down with them. These converters supply 12V DC power to lights, water pumps, slide-outs, and charge the house batteries. A failing WFCO typically shows symptoms like dim lights, slow-moving slides, and batteries that never reach full charge even when plugged into shore power.
What WFCO Converters Do
The WFCO converter takes incoming 120V AC power (from shore power or generator) and converts it to 13.6V DC for running 12V systems and charging batteries. It's essentially the heart of your RV's electrical system when you're plugged in. If the converter fails, your 12V systems will only run off battery power until the batteries are drained, and nothing will recharge them. WFCO units are known for using power transistors that can fail when subjected to voltage surges, overload conditions, or simple age-related fatigue. When these transistors short, the converter may still power on (LED indicators light up) but produce low or unstable voltage output.
Symptoms of WFCO Failure
The classic signs of a dying WFCO converter include: lights that are noticeably dimmer when plugged into shore power compared to running on batteries, water pump that barely runs, slide-outs that move sluggishly, and batteries that show low voltage even after being plugged in for 24 hours. You may also notice that lights flicker when high-draw appliances like the water pump kick on. A technician will measure voltage at the converter output terminals. A healthy converter should show 13.6V (float charge) or 14.4V (bulk charge mode). If readings are below 12.5V or fluctuate wildly, the converter has failed.
Fuse and Breaker Issues
Before condemning the converter itself, check all fuses and circuit breakers associated with it. WFCO units have both an AC input breaker (usually 30-40 amp) and multiple DC output fuses. If the main DC fuse or breaker has blown, it will appear as a complete failure of all 12V systems. These fuses are often hidden inside the converter compartment behind a removable panel. Also check the 120V AC breaker feeding the converter—this is usually in the main breaker panel labeled 'Converter' or 'Battery Charger.' If this breaker has tripped, the converter will have no input power.
Replacement vs Upgrade Options
If your WFCO is confirmed dead, you have two options: replace it with another WFCO unit (exact model replacement), or upgrade to a modern smart converter like a Progressive Dynamics PD9100 series. The PD units offer better battery charging profiles, higher output capacity, and more robust electronics. The mounting footprint is often compatible, making it a direct swap upgrade. Replacement requires working with both 120V AC and 12V DC wiring, so this is a job best left to a qualified technician or electrician familiar with RV systems.
⚠️ Safety Notes
- Always disconnect shore power and batteries before working on converter wiring—both AC and DC voltages are present.
- Never bypass fuses or circuit breakers 'temporarily'—this is a major fire hazard in RVs.
Can't fix it yourself?
Don't let a mechanical issue ruin your trip. Connect with vetted mobile RV technicians who can come to your location and get you back on the road.