Dexter Washer Error Code F15: Drive Over-Voltage
F15 means the voltage inside the drive is too high, from high supply voltage, electrical noise or the motor feeding energy back into the drive. A technician should measure the supply and check the braking resistor.
High: the drive stops on over-voltage and the washer will not complete cycles.
What does Dexter error code F15 mean?
The drive converts incoming AC to an internal DC voltage. If that voltage rises too high, the drive trips and the control shows F15, which the Common Washer guide labels DRIVE OV. There are two sources of high voltage. One is the supply: voltage above range or electrical noise on the line. The other is the motor: when it is slowed, it can generate voltage back into the drive, which the braking resistor is there to absorb. The manual's checks reflect both. Measure supply voltage at L1, L2 and L3, which should be 187 to 264 VAC, or 108 to 132 VAC on a 120 VAC drive, and make sure the connections are tight. Check the braking resistor connections at B2 and the values, 200 ohm for 1 and 2 hp and 160 ohm for 3 hp. On a 240 VAC high-leg supply, the manual suggests trying with the high leg disconnected or adding surge suppression or a line choke.
Affected models and control systems
Dexter T-450 SWD Express stack washer-dryers, serial 481983 and up. The same F10 to F21 table appears in the WCAD-Series vended washers manual (8533-073-001, 11/11). Older Dexter washers number their drive codes differently.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- F15 on the display
- Alarm during slowdown or after a power surge
- Cycle stops early
Possible causes
Listed in Dexter's documentation
- High input voltage or noise
- Motor back-feeding the drive
Other likely causes — what usually sits behind error code F15 on this control. A technician confirms which one it is before any part is replaced.
- High-leg supply raising one phase above range
- Braking resistor open or disconnected at B2
- Large equipment switching on the same feed
Safe checks before calling for service
- Press stop and let the cylinder come to rest.
- Power the washer off at its disconnect for about a minute, then switch it on again.
- Ask whether other machines on the feed show trouble.
- Note whether F15 appears during deceleration.
How a technician diagnoses error code F15
- Read the code and the VFD light code before power off.
- Measure the supply voltage at L1, L2 and L3 and check the connections.
- Check the braking resistor connections at B2 and measure its value.
- On a high-leg supply, test without the high leg or add suppression.
- Replace the resistor or drive after the checks.
- Supply and resistor tests are made on live 208-240 V circuits.
- High-leg wiring needs a qualified electrician.
- The drive stores energy after power off.
How error code F15 differs from similar codes
F15 is over-voltage; F19 is low voltage to the drive. F14 is over-current.
Technical reference
- Maker documentation
- Dexter owner support
- Edition
- Part # 8533-070-001 (12/13), starting serial number 481983
- Models / control
- Dexter C-Series and T-series coin washers with VFD (T-300 to T-1450)
- Section
- Troubleshooting Washer Fault Errors (F-Codes), p.6-10
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Dexter washer error codes
What is the braking resistor for?
It absorbs the energy the motor sends back while it slows down.
Can the building supply cause F15?
Yes, high voltage or noise are the first cause the manual lists.
What are the ohm values?
200 ohm for 1 and 2 hp, 160 ohm for 3 hp.
Need help with Dexter error code F15?
A technician confirms the cause on site and gives you the price in writing before any work starts.