When the outside temperature gets above 90 degrees, your RV refrigerator can have a difficult time trying to keep your food cool enough and your drinks cold. There are many things that can create your refrigerator from running efficient, like a dirty gas burner, the sun hitting the side of the motorhome that your refrigerator is on, dirty flew, or poor air circulation in the outside refrigerator compartment. If you have had your refrigerator serviced and it is still not cooling adequately, then it is time to install a cooling fan to improve the ventilation at the back of the refrigerator. By having the fan pointed up towards the vent it will direct the hot air out of the compartment.
If your refrigerator was installed incorrectly where there is dead space in the compartment it will prevent the convection action from working properly. The dead air space will trap the warm air and reduce the amount of draft to the upper vent. By adding the cooling fan it will help push the air out of the dead space and exit out the top vent. Refrigerators that are built into a slide are notorious for hot air getting trapped in the top part of the refrigerator compartment.
There are many different types of fans that can be used for this modification. It is best to find a fan that has a permanent mount and runs off the motorhome batteries. Computer fans that are 3 to 4 inches in diameter are a perfect match for this modification. They will use little battery power and can move a good amount of air through the compartment. Avoid fans that run off flashlight batteries, they will not last long and do not provide good air flow.
When looking for a fan you might want to consider one that is thermostatically controlled. The thermostat allows the fan to come on when the ambient air temperature reaches a set point. There are different temperature thermostats available but I would look for one that switches on at 90 degrees. You can also add a switch to the fan to override the thermostat. The best place to mount your vent fan is at the bottom of the vent stack near the lower vent.
Most RV parts store will sell after market refrigerator fans or you can check your local electronics or computer store.