How to Check a Thermistor in an RV Refrigerator

How to Check a Thermistor in an RV Refrigerator
If your RV refrigerator is filled with frost and your food is frozen, chances are you have a faulty thermistor. The thermistor is the part of your RV's refrigerator that senses temperature based on resistance. Thermistors commonly fail because their resistance level is higher than it should be, causing the temperature in your refrigerator to overcool. Because all RV refrigerators are designed differently, you'll need to refer to your RV refrigerator's owner's manual for the location of the thermistor, removal instructions and its resistance range so you can check whether it is the cause of the problem.

Instructions

Difficulty: Moderate

Things You’ll Need:
  • Thermistor
  • Ohmmeter
  • Glass of ice water
Step 1
Attach the ohmmeter leads to the thermistor's connectors. The connectors are the long metal pieces protruding from the thermistor's round plastic sensor.
Step 2
Put the thermistor's sensor into a glass of ice water.
Step 3
Wait 3 minutes.
Step 4
Check the ohmmeter reading and record it.
Step 5
Compare the ohmmeter reading with the resistance range referenced in your RV refrigerator's owner's manual. Check to see if the ohmmeter reading is within the resistance range. If not, then the thermistor is faulty.

Tips & Warnings

 
There are two main brands of RV thermistors, Dometic and Norcold. The Dometic thermistor has a resistance reading between 7,000 and 10,000 ohms. The Norcold thermistor has a resistance reading of approximately 40,000 ohms with the exception of the 900 series.
 
Always unplug your RV refrigerator before removing any circuit board parts.

Article Written By Elizabeth Grace

Based in Grand Rapids, Michigan, Elizabeth Grace is a freelance writer. She holds a Bachelor of Arts in public relations from Pepperdine University, and has 15 years of experience developing marketing campaigns for universities and multinational corporations.

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