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As temperatures heat up this summer, so does the frustration of an ineffective absorption or “RV” refrigerator!  And typically insufficient cooling of the refrigerator is in the top three service calls right up there with batteries and air conditioners.

To make your RV refrigerator run more efficiently in hot weather, it’s important to understand how the absorption refrigerator works.  A heat source such as a flame when operating on liquid propane (LP) or a heat element when operating on 120-volt power heats a solution of Ammonia, Hydrogen, Sodium Chromate, and Water that comes from the boiler vessel.  As the solution gets hot, it turns to a vapor and travels up to the condenser fins where the components separate at various stages and create a flashing that draws heat out of the freezer compartment.  

The solutions travel back through the cabinet evaporator fins which can be seen inside the main refrigerator cabinet and make their way back down to the boiler vessel to start the process over.  There are no moving parts in this system and the solution zig zags it’s way back down by gravity. 

Here are 5 tips to make your refrigerator run more efficient in hot weather.

It’s Important To Be Level

Since the solution needs to travel back down the zig zag tubes of the cooling unit, it’s important that your rig is level for this to happen.  Most refrigerator manufacturers state the unit should be level 3 degrees side to side, 6 degrees front to back.  Since most of us do not have a digital leveling device that could tell us that, a good device to use is a bubble leveler that is typically provided with your new refrigerator.

If the bubble is breaking the circle, it’s ok.  This is one of the biggest issues with RV refrigerators as many owners bring their rigs home before a trip, park it in the driveway, and plug into the garage to cool the refrigerator down and load it.  Most driveways are slanted to allow for rain runoff and well past the requirements for the solution to makes its way back to the boiler vessel.  When it happens, the solution pools in the cooling unit tube which makes it heat up and eventually flakes and blocks the flow of the rest of the solution until it becomes solid and the unit does not cool at all. 

Routine Maintenance

Since there are no moving parts, most owners think there is little or no maintenance required for their refrigerator other than cleaning it out.  After all, our residential refrigerator needs no maintenance unless I forget the Braunschweiger hidden in the veggie drawer!  However, for RV refrigerators, there are a few things you need to do at least once a year to make your unit run more efficient.

Clean the roof vent if your refrigerator is not in a slide out.  The heat generated in the back of your refrigerator compartment needs to vent out either through the top of the rig or on the side if your unit is in a slideout.  The roof top vent has a screen covering the rectangular exhaust commonly referred to as the flue which can get plugged and needs to be cleaned to allow the heat to exhaust out. 

Next, clean the burner assembly and other components to get rid of soot, obstructions from spiders and other inspects and dust.  Use an air gun blower and clean out the entire outside compartment shown here.  This is a blow gun purchased at an auto parts store with a ¼” clear hose on the end with a pinch clamp.  Wear safety glasses as this will provide a shower of soot and dust but will prevent additional heat from collecting on the components.

Check the door seals to make sure they are making a good connection.  Place a piece of paper or dollar bill between the door and frame, shut the door and try pulling the paper out.  If it tugs slightly, it is good, however if it slides out easily, it is not sealing and warm moist air can penetrate the inside.

Cool Your Food Before You Go

Don’t put warm food inside a warm refrigerator and expect it to get to 36 degrees anytime soon!  If possible, cool down food before camping and get your refrigerator to operating temperature before you leave.  A typical refrigerator can only reduce ambient temperature inside the cabinet about 10 degrees per cycle which means it can take over 24 hours to bring a unit down from 90 degrees to 36 or even more.  Plus, if you add warm food, it will take longer. 

Since the freezer is the first stage of cooling, I have found it’s easier to keep the rest of the refrigerator cool by putting 5 lb bag of ice in there if you have room.  The more stuff you have in the freezer, the cooler the temperature is in the main ref cabinet…from my experience.

Also, limit the amount of can items in the main cabinet as they have a tendency to create condensation which can collect on the evaporator fins and cause frost.  This will give a false temperature reading to the temperature sensor called the thermistor and the refrigerator will not cool efficiently. 

Make Sure There Is Good Airflow Inside

Heat rises and it’s not uncommon for a refrigerator to create pockets of hot and cold air as there is virtually no air movement inside your refrigerator.  Use a small 9-volt fan placed on the bottom shelf to get air moving evenly around the inside.  Do not put plastic or other liners on the shelves as this will also block the air flow.  Check to make sure the thermistor is not covered in frost, if so you will need to defrost the unit.  You may need to raise the thermistor to a higher position on the evaporator fins as hot air rises. 

Cool The Back Of The Refrigerator Compartment

If possible, park your rig with the refrigerator side in the shade during the heat of the day.  Direct sunlight in the afternoon will heat the compartment and make it difficult to keep up with the additional heat.  The addition of venting fans will also help move the heat out of the compartment to the roof vent or slideroom upper vent.

These should be placed above the cooling unit just under the evaporator coil.  Smaller fans placed at the bottom are ineffective as there is to much obstruction from the boiler vessel and other cooling unit components.

Quick Troubleshooting

If your refrigerator is not cooling efficiently, check the operation on both modes.  If it is cooling on LP better than 120-volt AC power, you can verify it’s not the cooling unit, rather something in the 120-volt AC operation.  Generally low voltage or a weak heating unit.  If it’s cooling on 120-volt AC, then it’s something in the LP operation such as low LP pressure from the regulator, dirty burner assembly, or erratic flame operation.


About the author: Dave Solberg: Managing Editor, RV Repair Club

For the last 25 years, Dave has conducted RV maintenance and safety seminars, developed dealer and owner training programs, written RV safety and handyman articles, authored an RV handbook reference guide and logged over 100,000 miles on the road in an RV.

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