RV AC Thermistor Failure: Causes & Fixes

Temperature sensor failed. Constant run, no cooling, erratic cycling.

🔎 30-Second Summary

RV AC thermistor failure can lead to improper cooling and erratic system behavior due to incorrect temperature readings sent to the control board. This issue is often found in older units and can be diagnosed through resistance testing and inspection of connections.

Generated from this page. Always verify technical specs.

System context: To understand how RV air conditioners work, see RV AC Not Cooling.

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AI Quick Summary: RV AC thermistor failure usually indicates:

Thermistor senses evaporator temp. Failed = wrong signal to control board. See RV AC not cooling and RV AC freezing up.

What This Problem Usually Means

The thermistor is a temperature sensor on the evaporator coil. It tells the control board how cold the coil is. A failed thermistor sends wrong readings—causing constant run, no cooling, or erratic cycling. The reader should feel instantly understood.

The 3 most common causes: (1) Thermistor out of calibration, (2) Failed open or short, (3) Loose connection.

Quick Troubleshooting Steps

  1. Step 1 – Resistance test: Use multimeter to measure thermistor resistance at room temp. Compare to spec (usually 10k–50k ohms).
  2. Step 2 – Connection: Check for loose or corroded connections at thermistor.
  3. Step 3 – Replace: If out of spec, replace thermistor. Match part number.
Still not fixed? If thermistor replacement doesn't resolve erratic cycling, control board or refrigerant may need professional diagnosis. Request local service below.

Related Troubleshooting Guides

RV AC Not Cooling · RV AC Freezing Up · RV AC Short Cycling · RV HVAC Hub

Frequently Asked Questions

What does RV AC thermistor do?

Senses evaporator temperature. Tells control board how cold coil is. Failed thermistor causes constant run, no cooling, or erratic cycling.

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About the Author

Adam Hall — Founder, DecisionGrid

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Updated March 2026 · Reviewed for technical accuracy

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Last updated: March 2026 · Reviewed for technical accuracy

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