I'm dealing with a frustrating issue with my Norcold N842IM refrigerator that's been happening consistently during our camping trips. The fridge works absolutely perfectly when we're plugged into shore power and running on AC - no problems whatsoever with cooling performance or any error codes.
The real problem starts when we disconnect from shore power and head out on the road. The refrigerator switches over to propane mode without any issues initially, and everything seems to be working normally for the first several hours. However, after approximately 8-9 hours of running on propane, I consistently get an alarm and a 'no CO' error code displayed. I've been turning the refrigerator off for about an hour (though I'm not sure if that's the right amount of time), and when I restart it, it runs fine for another 8-9 hour cycle before the same error occurs again.
I'm wondering what could be causing this specific 'no CO' error to appear after this consistent timeframe when running on propane. Is this related to combustion problems, ventilation issues, or something with the propane system components? I'd really appreciate some guidance on what I should be checking and how to properly troubleshoot this recurring problem.
The 'no CO' error on your Norcold N842IM after 8-9 hours on propane is typically caused by combustion issues like a dirty burner, blocked flue, or faulty thermocouple. Start by cleaning the burner assembly and checking for proper ventilation.
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Your Norcold N842IM is experiencing a "no co" (no combustion) error after 8-9 hours on propane because the burner flame is being extinguished or the flame sensor is failing to detect proper combustion. This is a safety feature that shuts down gas flow when combustion isn't detected. Common causes include a dirty burner tube, spider webs or debris in the flue, a failing flame sensor, or inadequate gas pressure. The fact that it works fine on AC and initially starts on propane suggests the cooling unit itself is functioning properly.
The "no co" error on your N842IM specifically indicates the control board isn't detecting proper combustion at the burner. After 8-9 hours of operation, something is disrupting the flame or the sensor's ability to detect it. Common causes include debris accumulation in the burner assembly or flue system that builds up during operation and eventually blocks proper air/gas mixing or flame stability.
Another common cause is the flame sensor becoming contaminated or failing intermittently as it heats up during extended operation. The sensor needs to maintain a specific temperature to signal proper combustion to the control board. Additionally, propane pressure can drop over time due to regulator issues, partially clogged orifices, or low tank pressure, causing an unstable flame that eventually fails.
The fact that turning the unit off for an hour "resets" the system suggests either the sensor is cooling down and temporarily working again, or debris is settling enough to allow proper combustion restart. This cyclical pattern is characteristic of contamination or sensor issues rather than major component failure.
WARNING: Before beginning any maintenance on your propane refrigerator, shut off the gas supply at the tank and allow the unit to cool completely. Propane work can be dangerous if not done properly.
Start by accessing the burner assembly from the exterior access panel on the back of your RV. Remove the cover and visually inspect the burner tube and flue for any obvious debris, spider webs, or corrosion. Use compressed air to blow out any debris from the burner assembly, working from the inside out to avoid pushing debris deeper into the system.
Next, examine the flame sensor (small probe near the burner). It should be clean and positioned properly in the flame path. If it appears dirty or corroded, carefully clean it with a soft brush or compressed air. The sensor should be positioned properly in the flame path according to manufacturer specifications. Test the sensor with a multimeter - check resistance values according to manufacturer specifications for proper operation.
Check your propane system pressure using a gauge at the regulator. Proper pressure should be 11 inches of water column (about 0.4 psi). If pressure is low or fluctuating, the regulator may need replacement. Also inspect all gas connections for leaks using soapy water - look for bubbles that indicate escaping gas.
Clean the flue and chimney area thoroughly, as accumulated soot or debris can affect proper combustion airflow. Use a vacuum to remove loose debris, then inspect with a mirror or smartphone camera to ensure the flue is completely clear. Finally, check that the refrigerator is level, as being off-level can affect both cooling performance and proper gas combustion.
Call a certified RV technician if you discover any gas leaks during your inspection, as this requires immediate professional attention for safety reasons. Also contact a pro if the flame sensor tests show it's completely failed, as replacement requires precise positioning and calibration to ensure safe operation.
If your troubleshooting reveals that the control board itself is malfunctioning or if you're uncomfortable working around gas appliances, professional service is warranted. Additionally, if cleaning the burner assembly and flue doesn't resolve the issue after a full day of testing, there may be internal cooling unit problems that require specialized diagnostic equipment and expertise.
Consider professional service if your RV is still under warranty, as DIY gas appliance repairs might void coverage. For the N842IM, expect repair costs ranging from $150-300 for sensor replacement to $800-1200 if the cooling unit needs replacement, though your symptoms suggest a much simpler fix is likely needed.
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