Our last RV trip indicated the need for quicker refrigerator cooling in hot weather. Mainly my fault.
It was especially evident when I turned OFF our refrigerator when we had to park way off level in some parking lots (and I forgot to turn the fridge back on)
Once for 3 hours, and once for 2 hours (100 degrees outside), with the sun was on the refridgerator wall.
Have wanted to add a refrigerator chimney fan/s for some time now. Knew I wanted a master on/off switch, and a thermostatically controlled fan switch. This way the fans can cycle on and off automatically. The first job was to order a new roof vent and base. The old style from Dometic is now obsolete.
: The new Dometic refrigerator roof vent base is a good inch wider than the original. Depending on your rig, this extra width may become a mounting issue. In our case I had too centering the new base over the existing metal roof frame work. Some of the screws needed to be put in at an angle to catch the metal under the rubber roof. The other thing I noticed is the new vent had less than half of the mounting holes drilled, verses the original. Had to drill an extra hole between each existing pre-drilled hole in the base.
After removing the roof vent I noticed that one, of the two, fiberglass insulation pads had fallen on top of the condenser fins. A good 6 inches of the fins were block from air flow. The second thing I noticed was that the top of the refrigerator, and the cabinet walsl (above the fridge) wasn't insulated either. Lastly there was no baffle to direct the air to the chimney above the fridge. Used some of the left over insulation, from our engine dog house project, to cover the uninsulated areas. Insulated the top of the refrigerator, and made a baffle to direct the air flow up the chimney. The insulation should help keep the fridge and cabinet, above the fridge, stay cool.
Used four 92mm computer fans, too (almost completely) fill the chimney cut out. Cut some aluminum plates to bolt the fans to each other, and suspend the fan assembly from the roof opening. This should make repair or replacement easy in the future.
Wired the fans together, and ran the wires down inside the chimney. An adjustable thermostatically controlled switch was mounted to the evaporator tube (see the phot below). The master on/off switch is mounted inside the fridge cavity, behind the exterior access panel. Also added a led to indicate when the fan circuit is activated. (see photos)
The actual build and install took way, way longer than I ever could have imagined. Still need to Dicor the roof vent (tomorrow). Verdict:
The four fans draw enough air to hold a 8.5 x 11 sheet of paper to the fridge access cover. At the moment I have the thermo switch set to turn on at 100 degrees and off at 80 degrees. Real-world testing will tell me if I need to adjust up or down from there.