I'm at my wit's end with my 7-year-old absorption fridge (Maybe-Cold N8X, Serial 28221668). This thing is driving me absolutely crazy! It heats up just fine on both AC and propane - no issues there at all. But the cooling is completely unpredictable. Sometimes it works perfectly, other times it just stops cooling for no apparent reason, even in the middle of the night when temperatures are stable.
I've been tracking temps with data loggers and can see it just randomly stops cooling even though there are no error codes flashing. The thermostat tests good at about 8k ohms at 85°F, which matches what the service manual says it should be. I've got fans helping with air circulation and exhaust ventilation, so I don't think it's an airflow problem.
Before I throw in the towel and replace this entire fridge, what should I be checking? Is this a cooling unit failure, or could it be something with the control board or sensors? I really need to figure out what's actually failing here because this intermittent cooling is making our trips miserable!
Your RV absorption fridge's intermittent cooling is likely caused by a failing cooling unit, blocked thermistor, or control board issues. Check the thermistor connections first, then test the control board before considering cooling unit replacement.
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Your 7-year-old absorption fridge is experiencing intermittent cooling failures without error codes, which points to either a failing cooling unit (the coils/ammonia system) or thermal control issues. Since you've verified the thermostat is reading correctly (verify exact resistance specifications with manufacturer documentation) and the heating elements are working on both AC and propane, the problem is likely in the ammonia absorption system itself. The fact that it suddenly stopped cooling in the middle of the night while operating normally suggests either a partial blockage in the cooling unit or the ammonia solution has become contaminated over the 7 years of operation.
The intermittent nature is actually worse news than a complete failure - it typically indicates the cooling unit is on its way out but hasn't completely failed yet. Your setup with exhaust fans and circulation fans is excellent and rules out most ventilation issues that cause similar symptoms.
Absorption fridges work by heating an ammonia-water solution, which creates a cooling cycle through evaporation and condensation. Over time, especially after 7 years, several things can go wrong. Common causes include crystallization or chemical breakdown in the ammonia solution, which creates pockets that block proper circulation. This causes the intermittent cooling you're experiencing - sometimes the blockage clears temporarily, other times it doesn't.
Another common issue is crystallization in the generator section, where the ammonia solution can form crystals that partially block flow. This is exacerbated by the fridge being level during operation - even small deviations from level over years can cause sediment buildup in the cooling coils.
The sudden nighttime failure pattern you're seeing may occur because any partial blockages become more problematic when the system has been running for extended periods, and thermal cycling can affect intermittent blockages. Note that cooling unit longevity can vary significantly between individual units and model years.
Before diving into major repairs, you'll need to do some diagnostic work that goes beyond what you've already done. Get a infrared thermometer to check temperatures at different points along the cooling coils - you're looking for unusual temperature variations that indicate blockages. You'll also want to monitor the fridge over several complete cycles, noting ambient temperature, operating mode (AC vs propane), and any patterns in the cooling failures.
Gather your tools: multimeter, infrared thermometer, bubble level (check if the RV has settled unevenly), and a borescope or small mirror to inspect the cooling coils from underneath. Document everything with photos and temperature readings. If you're comfortable with basic electrical work, you'll also want to test the control board's output voltages to the heating elements during operation.
The data you've collected is gold - create graphs showing ambient temperature vs fridge temperature over time, and note exactly when failures occur. This pattern will help determine if it's truly a cooling unit failure or something else like thermal expansion issues in the control system.
Start by checking the cooling unit from underneath your RV. Look for any signs of yellow powder or staining around the coils - this indicates ammonia leakage and means the cooling unit is definitely shot. **WARNING: If ammonia leaks are suspected, ensure adequate ventilation and avoid prolonged exposure. Ammonia has a strong odor and can be harmful in enclosed spaces.** Use your infrared thermometer to check temperatures along the coils during operation. You should see a gradual temperature decrease from the boiler section to the evaporator. Hot spots or areas that don't cool indicate blockages.
If the cooling unit looks physically intact, try the "burping" procedure: turn off the fridge completely and allow it to sit unpowered for several hours to help any blockages settle. Some owners report success with this passive approach. Some owners have success with gentle tapping on the cooling coils, though this is controversial. WARNING: Be extremely careful when tapping cooling coils as excessive force can damage the unit and cause ammonia leaks. Use only light tapping with a rubber mallet or similar soft tool. Leave it tilted for several hours, then return to level and restart.
Test the control board by measuring voltage output to both AC and propane heating elements during operation. Your control board should show consistent voltage output. If readings are erratic, the board may be failing intermittently. Replacement control boards run about $180-250, while a complete cooling unit replacement is $800-1200 plus labor.
Document everything with your graphs and temperature data. If the burping procedure works temporarily but the problem returns, you're looking at cooling unit replacement. If voltage readings from the control board are inconsistent, start there as it's much cheaper and easier to replace.
Cooling unit replacement requires removing the entire fridge from the RV, which involves disconnecting gas lines, electrical connections, and often removing interior cabinetry. WARNING: Gas line work requires proper safety procedures and may require certified technicians depending on local codes. This is definitely professional territory, typically running $1200-1800 total including parts and labor. Given your fridge's age and the intermittent nature of the problem, many techs will recommend complete replacement rather than cooling unit repair.
If you're considering replacement, newer 12V compressor fridges offer much better reliability and efficiency than absorption units. A comparable capacity 12V fridge would run $800-1200, but installation is more complex due to higher power requirements. However, given your excellent documentation and troubleshooting skills, you might consider this an opportunity to upgrade to more reliable technology.
The decision point is cost vs reliability: if a cooling unit replacement costs $1500+ and your fridge is already 7 years old, you might get better long-term value from a new unit. Professional diagnosis typically runs $100-150 and can give you definitive answers about whether the cooling unit or control board is the culprit. Your detailed data will be invaluable to any tech working on this problem.
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