Monday, September 25, 2023


How important is leveling for an RV absorption fridge?

Dear Gary,
We recently purchased a used 2007 motorhome and haven’t actually camped in it yet but have done some local driving to get used to it. We’ve been reading about the leveling for the refrigerator and understand the necessity. We have a two-door unit (top freezer and bottom refrigerator). My husband is concerned about leveling while driving such as on hills and mountains. Should we be concerned? —Rosemary P.

Dear Rosemary,
Leveling is important during any operational mode (12-volts DC, 120-volts AC or propane), but only while the coach is stationary. When physically moving down the road, there is enough jostling and movement to keep the liquids and vapors safely flowing through the sealed system of the absorption refrigerator.

It is only crucial when the vehicle is not in motion. And with today’s cooling core design, it’s not as crucial as it used to be. Today, as long as the motorhome is “relatively” level, the cooling unit will be safe.

I once asked a refrigerator manufacturer what “relatively” level really meant and the bottom line is this: If the eggs don’t roll off the countertop or if the blood doesn’t rush to your head while sleeping, the refrigerator will be fine. However, while standing still, try to get it as level as possible. It’s just not worth the risk, in my opinion.

Operating the refrigerator off-level creates an inordinate amount of heat at the rear of the unit, especially in the boiler area. Coupled with improper ventilation, this extra heat can escalate very quickly into potential costly troubles.

When overheating occurs over a period of time, the sodium chromate inside the pipes begins to crystallize (sodium chromate is used to protect the insides of the tubing from the corrosiveness of the ammonia).

Typically the blockage will occur in the percolator tube, one of the smallest of the internal tubes inside the cooling core. The percolator tube inside the boiler section can become impassable because of the blockage (see photo). When this happens, the cooling unit is blocked and cannot be repaired. It must be replaced with a new or reconditioned unit.

Leveling is one of the two most important factors to consider when using the RV absorption refrigerator. As mentioned, the other is ventilation. There must be a continuous, chimney-like ventilation space behind the refrigerator all the way up and through the roof. But tell your hubby, as long as he keeps moving he need not be concerned.

gary-736Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.




    • Me too, Eileen. Every time I run across an article of Gary’s, or see his smiling face, it chokes me up. 🙁 —Diane at

  1. I always read advice about leveling the fridge, but never the real reason. It isn’t about level, it’s about gravity. The return tubes that cross back and forth across the back of the fridge work by gravity flow. They slope down back and forth across the back of the fridge. If you’re off level by about 3 degrees those tubes are level, not sloping down back and forth as they cross from side to side slowing or stopping the gravity flow of the ammonia return to the bottom. What I never hear from the experts is that side to side level is important for the fridge, but not front to back so much at all. Being way off level perpendicular to the gravity flow tubes would affect the gas burner flame slightly, but have little effect on the ammonia flow. I think about this when I read a comment above that worries about parking on a street where you lean to the curb. No big deal if your fridge is mounted along an exterior wall … as most are. Of course, shutting it off is not a bad idea if you’re gone for hours. 🙂

  2. There’s another instance that might harm the fridge that most people might not think about. Most people think about leveling their campsite, but what if you’re travelling to an event or place where the rv is going to sit for the rest of the day in a parking lot or on a street that is not level. If it sits there off level for 6-8 hours, with the fridge running, I would assume that would not be good for the fridge. The fridge should probably be turned off when you arrive at the spot to park. I assume the fridge would not be damaged if it’s turned off, & the inside food temp would not go up more than a couple of degrees during that time

  3. If you add a product called “fridge defend” (about $200), it will shut down your unit when the boiler gets too hot and restart it when it cools down. You can also add a auxiliary blower that cools the coils and comes on sooner than the factory fans. I put this on mine and it works great. The blower hardly uses any power so does not affect our boondocking ability.


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