Welbilt FB081TF, Service Manual

Page: 46 / 96

46 Part Number REV00 04/08/2020
Troubleshooting Section 5
Check Thermistor
SPECIFICATIONS
• 5,000 Ohms ± 2% at 25°C (77°F)
• 16,330 Ohms ± 2% at 0°C (32°F)
NOTE: These values are only for the white probes that go
to the Syrup Storage and Syrup Nozzle probes. The Blue
Evaporator Probe has a different resistance range.
CHECK PROCEDURE
NOTE: Use a multimeter to check operation.
1. Reboot machine by moving rocker switch OFF/ON.
2. Inspect for correct wiring.
3. Isolate by disconnecting the wiring connectors on SRB
J32 Temp Drive 3 / Cabinet Probe 1.
4. Check continuity across the terminals with an ohm
meter.
- Resistance = Thermistor is good
- Open (OL) = Replace thermistor
NOTE: These thermistors are identical. Swapping the
thermistor connections at the IO board can be used for
diagnostics. See “Temperature Thermistor - Nozzle &
Cabinet probes only” on page 77.
Check compressor relay on SRB
With power disconnected, check the compressor relay
that is mounted on the SRB. The compressor relay is the
largest relay on the SRB and has two terminals exposed that
can be checked for continuity. The exposed terminals are
the Common (C) and the Normally Open (NO). If there is
continuity between the terminals with power disconnected
to the unit, the relay contacts are defective and the SRB
should be replaced.
HIGH PRODUCT TEMPERATURE
Check Duct Cooling Fan
• Product temperature is greater than 42°F.
• Verify the door was not left open or warm product was
added.
• Reboot machine by moving toggle switch off/on.
• Verify duct fan is operating.
• Allow machine to run for 15 minutes then prime each
product.
• If fault remains check duct temperature with a digital
thermometer to determine if refrigeration or thermistor
diagnostics need to be performed.