How to Check Thermostats and Thermistors in Your Appliances

How to Check Thermostats and Thermistors in Your Appliances

When your appliances aren’t heating, cooling, or maintaining proper temperature, the problem may not always be with the main motor or compressor. Often, faulty thermostats and thermistors are the culprits. These small but critical components help regulate temperature, ensuring your appliances run efficiently and safely. At PRS Parts Inc., we provide OEM (Original Equipment Manufacturer) replacement parts so you can keep your machines running like new.

Understanding the Difference: Thermostat vs. Thermistor

  • Thermostat: A mechanical or electronic switch that opens or closes based on temperature, commonly found in ovens, dryers, refrigerators, and dishwashers.

  • Thermistor: A temperature-sensitive resistor that changes electrical resistance based on heat levels. It’s commonly used in refrigerators, freezers, washing machines, and dishwashers for precise temperature control.

Both play important roles, and when they fail, you’ll often notice inaccurate heating or cooling cycles.

How to Check a Thermostat

  1. Unplug the Appliance
    Always disconnect from power before testing.

  2. Locate the Thermostat

    • In ovens and dryers, thermostats are usually near the heating element.

    • In refrigerators, they are typically in the control housing or behind panels.

  3. Remove the Thermostat
    Take out the component carefully to avoid damaging wires.

  4. Test with a Multimeter

    • Set your multimeter to continuity mode.

    • Place the probes on the thermostat’s terminals.

    • A good thermostat will show continuity when closed (room temperature for most appliances) and no continuity when open (after reaching set temperature).

  5. Replace if Necessary
    If the thermostat does not show proper continuity, it should be replaced with an OEM part for reliability.

How to Check a Thermistor

  1. Disconnect Power
    Always unplug before working with electrical components.

  2. Locate the Thermistor

    • In refrigerators, it’s often clipped near the evaporator coils or behind interior panels.

    • In washers, it may be near the tub or water inlet valve.

  3. Remove and Inspect
    Look for any corrosion or visible damage.

  4. Test with a Multimeter

    • Set your meter to measure resistance (ohms).

    • Place the probes on the thermistor’s terminals.

    • Compare the resistance reading with the manufacturer’s specifications (values change with temperature). For example, many refrigerator thermistors measure around 10k ohms at room temperature.

  5. Check for Fluctuations
    Warm the thermistor slightly (hold in your hand) and watch for resistance changes. If resistance does not change, the thermistor is faulty.

Tips & Tricks for Extending Appliance Life

  • Regular Cleaning: Dust and debris buildup around thermostats and sensors can cause false readings.

  • Avoid Overloading: Overstuffing refrigerators, freezers, or dryers makes thermostats work harder, shortening their lifespan.

  • Check Ventilation: Blocked vents can cause overheating and inaccurate readings.

  • Replace Early: If you notice temperature inconsistencies, replace thermostats and thermistors before they cause further damage to compressors, motors, or heating elements.

When to Call a Professional

While checking and replacing thermostats and thermistors can often be a DIY repair, some situations—like sealed system refrigerator issues or electrical complications—are better handled by a certified technician.

Final Word

Faulty thermostats and thermistors can cause a chain reaction of problems in your appliances. The good news? They’re usually affordable and straightforward to replace. At PRS Parts Inc. at 540 Lagoon Dr., we stock a wide range of OEM thermostats, thermistors, and other replacement parts to keep your appliances in top condition.

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