Most likely causes (in order of likelihood)

  1. Failed or unplugged fresh-food compartment fan (the most common cause on newer fridges).
  2. Ice buildup on the evaporator fins blocking cold air transfer to the fridge section.
  3. Failed or shifted thermistor — the small sensor clipped to the cooling fins inside the fridge.
  4. Worn or torn door gasket allowing warm air to leak in faster than the fridge can cool.
  5. RV not level (absorption fridges only) — even 3° off can stop cooling.
  6. Failed cooling unit — the expensive one. Suspect this last.

Diagnostic steps (in order, free/cheap before expensive)

  1. Verify the RV is level. Use a bubble level on a shelf inside the fridge. Even slight off-level will kill an absorption fridge.
  2. Open the fridge and listen. If your model has an interior fan, you should hear it run. Silence means the fan has failed (typical part: $30-$80).
  3. Locate the thermistor — a small bulb-shaped sensor clipped to the cooling fins. Make sure it's seated firmly. Highway vibration can shift it.
  4. Test the door gasket. Close the fridge on a dollar bill. If it pulls out with zero resistance, the seal is leaking. Replace it.
  5. Defrost completely with both doors open for 24 hours. If it then cools normally but fails again within a week, you've confirmed a fan or thermistor problem.
  6. If none of the above resolve it, the cooling unit is likely failing. Replacement runs $1,200-$2,000 installed on absorption models.

DIY vs. call a tech

Steps 1-5 are DIY for any owner with basic tools. Step 6 (cooling unit replacement) is a certified RV tech job.