Description
Dometic RV Refrigerator Thermistor Assembly 3851059042
This Dometic thermistor assembly (part number 3851059042, also listed as 38510590422) is the temperature sensor used on many Dometic RM-series absorption refrigerators. It clips onto the cooling fins inside the fresh-food compartment, and the refrigerator's control board reads it to decide when to start and stop cooling.
Superseded part: Dometic's newer replacement for 3851059042 is thermistor 3851210025, which also replaces 2931863035 and 2931863076.
What the thermistor does
A thermistor is a resistor whose resistance changes with temperature: it rises as the sensor gets colder and drops as it warms. The control board measures that resistance, compares it to your temperature setting, and cycles cooling on and off to match.
When the sensor fails or reads incorrectly, the refrigerator loses track of the cabinet temperature. On many Dometic models the control runs the cooling unit continuously if it can't read the sensor, which is why a bad thermistor so often shows up as a fridge that freezes everything.
Signs your thermistor may need replacing
- Food in the fresh-food compartment freezes regardless of the temperature setting
- Changing the temperature setting makes little or no difference
- Poor cooling or no cooling
- The cooling unit seems to run nonstop
How to test it before you buy
Dometic's service procedure for RM-series refrigerators uses an ice-water test:
- Unplug the thermistor lead from the control board.
- Place the sensor end in a glass of ice water at about 33–35°F (0.5–1.5°C).
- Wait 2–3 minutes, then measure resistance across the two leads with an ohmmeter.
- A good thermistor reads roughly 7,000–10,000 ohms. A reading well outside that range, or an open circuit, means the sensor should be replaced.
Test procedures and values can vary by model, so check your refrigerator's service manual.
What's included
As shown in the product photos: the thermistor sensor on its lead with a 2-pin plug, a fin clip, and a COLDER/WARMER position label.
Installation
- The sensor end clips onto the cooling fins inside the fresh-food compartment. Mount the new one in the same fin position as the old one.
- The lead routes to the refrigerator's control board. On many models the board is reached through the exterior refrigerator access vent.
- Turn the refrigerator off and disconnect power before unplugging anything at the board.
- Tools: usually none for the clip and plug. Allow 10–30 minutes depending on board access and wire routing.
Fits these Dometic refrigerator models
Before ordering, confirm against the part number on your old thermistor or your refrigerator's parts list. Dometic uses different sensors on some families (for example the RM/RML 8-series, NDA1402 and CFX portable coolers). Not sure? Send us your model and serial number and we'll confirm the fit.
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Browse all Dometic RV refrigerator thermistors.
Product details
- Brand: Dometic
- Part number: 3851059042 / 38510590422
- Part type: Thermistor (temperature sensor) assembly
- Application: Dometic RV absorption refrigerators (RM series)
- Function: Senses fresh-food compartment temperature for the control board
FAQ
Can a bad thermistor make my RV fridge freeze everything?
Yes, it's the most common symptom. If the control can't get a valid temperature reading, many Dometic models keep cooling continuously.
Will moving the thermistor on the fins change the temperature?
On many Dometic models, yes — fin position affects where the refrigerator cycles. Start in the factory position (where your old sensor was clipped).
