What’s the Main Cause of Failure in RV Refrigerator Cooling Units?
An overheating RV fridge boiler section is one of the top reasons a camper’s cooling unit fails. In this post, we will look at how an overheating boiler section affects the performance of your fridge and what you can do about it.
The boiler section is part of the RV refrigerator, where either electric or propane heat starts the refrigeration process. When a cooling unit is operated level, has the correct heat input, and has good ventilation, the unit runs at a safe temperature (with just a few exceptions) and can expect a long, happy life. But bad things happen to the cooling unit when one of these components is missing.
When the cooling unit reaches a critical temperature, the refrigerant in the system starts breaking down. This may be noticeable in small increments by a fridge that doesn’t get as cold as it used to and progressively gets worse, or the unit suddenly ruptures in the boiler tubing, causing a release of all the refrigerant. Fatigue cracks in the boiler tubing cause these ruptures.
Here are 2 reasons why fatigue cracks form in the boiler tubing:
First: Heating of the boiler by its heat sources causes thermal expansion and contraction along the weld seams. Every time the unit cycles on and off, thermal expansion takes place. The tubing that the factories use isn’t heavy enough to handle the stress and eventually forms stress cracks along the welds in the boiler.
Second: Overheating causes a breakdown of the refrigerant and its additive sodium chromate. The brown sludge is sodium chromate that reached a critical temperature and solidified. Along with the sludge chromate are also flakes of metal from the interior walls of the boiler. When the sodium chromate breaks down, the interior walls of the boiler tubing are destroyed, which makes the already too-thin tubing even weaker until fatigue cracks form, causing a release of the refrigerant ammonia and hydrogen.
In fact, several RV fires in recent years have been linked to boiler failure in the cooling unit. Even if a fridge fire isn’t the result, the cooling unit is still destroyed and in need of replacement.
First, for your RV refrigerator to work correctly, it must fulfill these three conditions:
Must be level, while stationary. The refrigerator must be level front to back, and side to side per the manufacturer’s specification. While traveling, the refrigerator does not have to be level because liquids inside are sloshing around.
Must have the correct heat input.
The cooling unit must have good ventilation.
Well, today’s recreational vehicles don’t always meet these requirements. RV owners are often boondocking in unlevel parking lots, pulling up and down long steep grades. In addition, many towable campers don’t sit level on the tow vehicle.
Each of these issues will overheat the cooling unit boiler, damaging both the refrigerant and the boiler tubing, thus significantly shortening the life of the refrigerator. The unlevel operation can destroy a cooling unit faster than almost anything else and, if extreme enough, can ruin the cooling unit in a matter of hours.
Here are a few reasons why new RV refrigerators don’t last as long as older ones.
They are Quickly and Cheaply Built – Most modern RV fridges are not built to last compared to their older counterparts. Most are built with less sturdy materials, so they can’t withstand wear and tear. Their components are also harder to repair.
Incorrect Operation – As described above, improper RV fridge operation can affect how long it will last.
Ventilation Problems from the Way Some RV Manufacturers Install them – The biggest ventilation problems are with RV refrigerators installed in a slide-out room. An RV owner can do everything right and always level the RV/camper. Yet, the refrigerator can still fail suddenly from overheating due to ventilation problems with the slide-out room. Because the slide-out room doesn’t have a roof vent, the refrigerator relies on cooling fans to keep the unit from overheating. If the fans fail or the limit switch doesn’t turn the fans on at the right time, the cooling unit can be destroyed quickly. In extreme heat, even properly operating fans aren’t always enough to keep the cooling unit from overheating, especially larger refrigerators like the Norcold 2118, 1200LRIM 1210LRIM, and the Dometic NDR1292, RM7732, RM1350