Taylor Slush Machine Error Code Thermistor Open: Probe Reads Open

What does Taylor Thermistor Open mean?

Each freezing cylinder has a thermistor probe, a small sensor whose resistance changes with temperature. The control reads that resistance to know how cold the product is. When a probe reads as open, as if its circuit were cut, the control gets no usable temperature from that barrel. The display shows Thermistor Open. Without the signal, the control cannot judge how cold the product is, and the barrel may freeze too hard, run too warm or stop freezing until the circuit is repaired. The manual lists a freezing cylinder thermistor that has opened internally, a probe lead that is loose or snapped near the plug, a connector at the control that has pulled out, and a barrel input channel that gets no thermistor signal. Because there is one probe per barrel, the message may involve the left or the right cylinder, and knowing which one speeds the repair.

Affected models and control systems

Taylor Model C300 frozen carbonated beverage / slush freezer.

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

• Thermistor Open appears for one or both barrels
• The product in one barrel freezes too hard or stays soft
• The control cannot show a sensible barrel temperature

Possible causes

Listed in Taylor's documentation

• A freezing cylinder thermistor that has opened internally
• A probe lead that is loose or snapped near the plug
• A connector at the control that has pulled out
• A barrel input channel that gets no thermistor signal

Other likely causes — what usually sits behind Thermistor Open on this control. A technician confirms which one it is before any part is replaced.

• A probe lead flexed and cracked each time the barrel is removed for cleaning
• A connector loosened by vibration from the compressor

Safe checks before calling for service

How a technician diagnoses Thermistor Open

1. Read the message and note the barrel.
2. Check the probe plug and lead for damage, with power off.
3. Measure the thermistor resistance at a known temperature.
4. Inspect the connector at the control.
5. Test the barrel input channel with a substitute resistor.
6. Replace the thermistor or control only after the test.

How Thermistor Open differs from similar codes

Thermistor Open reads as a cut circuit. Thermistor Short on the same machine reads as the two leads touching.

Technical reference

Document

Model C300 Operator's Manual (updated 9/2/2020), User Interface p.5-2 to 5-4

Edition

055072-M; original publication 9/26/08, updated 9/2/2020

Models / control

Model C300 frozen carbonated beverage / slush freezer

Section

Section 5 User Interface - Table 5-1 Fault Messages p. 5-2 (PDF p. 20); fault explanations pp. 5-3 to 5-4 (PDF pp. 21-22)

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.