Need to turn on frig fan when TM is closed?

[Bailey'sMom]

Hi all

I just got thru the week from hell and just got camper all closed up hooked up and ready to go tomorrow morning for a two week much needed vacation.

Then I realized that while I turned the fridg to battery I forgot to turn on the fan! Crap!

Question.....do I have to open it up again and pop up just to turn on the fan, and if I don't what damage might I cause?

Please answer ASAP. Thanks all!

[inghamm]

I don't see anyone answering so I'll put in my 2 cents.
I have forgotten to turn that switch on. The big result is that the fridge works even worse than usual, since the absorption fridge needs the part of the area that the fan feeds cool air to needs to be cool as possible for it to work well.

[Shane826]

Too much heat from the refrigerator vents can warp or discolor the shell wall that's folded over it. Keep in mind these refrigerators make heat to get cold.

Heres what I've done in the past when I forgot to turn on the fan or even turn on the fridge; just open the front shell and latch the aluminum bars in place. Climb up on the tongue, climb over the slide (still pushed in), then I can slither past the chair to the control panel. You have a dinette model so that may be a little more difficult but I'm guessing you're smaller than me so you should have an easier time once inside the TM.

[commodor47]

I would open the trailer and turn on the fan. Otherwise the heat that builds up has nowhere to go. At the very least it will make it difficult for the refrigerator to cool down and could cause a problem with the shell interior wall. We've done that before and were able to open just the outer shell, carefully crawl into the unit from the front A-frame and reach the fan switch to turn it on.

Dick

[pmhellings]

An update on this thread: I have been on the road for 10 days and have moved the camper on 6 of those days. With fridge on 12v while towing, even connected to my TV ( 2013 Tacoma 4x4 ) and 200 watts of solar power, the batteries slowly lose voltage. I'm going to upgrade the wiring in the TV when I get back.

Paul

[ThePair]

Yes, you need this fan on. There is heat build up in that cabinet otherwise, and things like the electronics back there could potentially be damaged. Fan always needs to be on if the fridge is on and the shells are closed.

Some of us wired up a switch to turn the fridge on battery from the outside. I went one step further and also tied the fan into that same switch, so if I forget to turn it on inside, it'll still go on when I flip the switch on the outside.

[Bill]

This question made me wonder - has anyone ever installed a thermal switch in the refrig compartment, to turn the fan on and off automatically? For less than $10, Amazon has switches that will turn ON at (for example) 80 degrees, and OFF at (for example) 65 degrees. I imagine that switches with somewhat different activation temps are available. I'm thinking that 110 ON / 90 OFF might be a better choice.

Maybe wire it in series with the inside switch (which you would them leave on most of the time) for positive control.

The outside switch in parallel is probably simpler, though not self-actuating.

Bill

[ThePair]

Originally Posted by Bill

This question made me wonder - has anyone ever installed a thermal switch in the refrig compartment, to turn the fan on and off automatically? For less than $10, Amazon has switches that will turn ON at (for example) 80 degrees, and OFF at (for example) 65 degrees. I imagine that switches with somewhat different activation temps are available. I'm thinking that 110 ON / 90 OFF might be a better choice.

Maybe wire it in series with the inside switch (which you would them leave on most of the time) for positive control.

The outside switch in parallel is probably simpler, though not self-actuating.

Bill

It's an interesting thought, for sure. I do recall some discussion around this, but usually relating to fans on the top outside vent, not the in-built vent for closed-shell operation.

True, parallel isn't self-actuating, but my DC doesn't work without it on, anyway, so I always remember to turn it on, else I have nothing.

[rickst29]

Originally Posted by Bill

This question made me wonder - has anyone ever installed a thermal switch in the refrig compartment, to turn the fan on and off automatically?

As some TMO members recall, I used to have a slightly complicated set of PID-Controlled Ralays which ran both the external fans and the Fridge itself (electric modes only), itself according to fridge-interior temperature. But that was complicated - Bill's idea is easy, and really good. Here is the part to buy: http://www.ebay.com/itm/DC-12V-F-Fah...-/141777090187

You also need: A wirecutter/stripper, 2-4 wire nuts, electric tape, some THIN electric wire segments (black or red, and white wire), a few zip ties, a couple of SS sheet metal screws to hold the Thermostat in place.

Choose a mounting spot behind the Fridge. The Temp Sensor arrived wrapped into a coil; when uncoiling and mounting the temp sensor, do NOT create a sharp bend in the Temp Sensor cable. (Because the resistance in the cable is critical for accuracy, and kinks will increase resistance.) Uncoil the two ends enough to reach the Temp Sensor leads, and to mount the Sensor itself (above, but not touching, the top Radiator of the Fridge). Use zip ties to hold that end in free air, and more zip ties to keep the "extra length" coiled in a circle. Connect the leads of the Temp Sensor Cable into the Thermostat.

Cut one of the fan power connectors (doesn't matter whether it's "+" or "-"), and connect the cut ends through the "switched load" terminals of the Thermostat. If necessary, you can add a jumper wire, lengthening one (or both) of your cut wires to reach to your Thermostat location.

Open up an existing TM +12V wire nut (or cut into a TM +12V supply wire and use a new wire nut), to add a small small +12V power supply wire into the Thermostat power terminal (#18 wire is adequate, current flow will be very low). Connect a small "white wire" to the Thermostat power "-" terminal, and connect the other into a TM "white" wire grounding wire nut.

Now it turns on, and you can program: Set mode (HC) to "C" for cooling, set "Temp" Value (T) to 100, and set "Displacement" value (D) to 3. Done! When the "below-sink" switch in ON, the Thermostat will turn the fan on at 103F, and turn it back off when the measured temp falls below 100 F.

The thermostat adds a "phantom load" of about 3W, at all times. If you normally disconnect your batteries from TM in storage to avoid phantom loads, you'll need to re-do the programming when you plug in your batteries for a trip.

[Bill]

Hmmm, I've go to go through this in more detail, but it occurs to me that I might not have been totally clear in my original suggestion. What I meant to suggest is to install a thermal switch to sense the air temperature BEHIND the refrig, up near the top of the compartment where the heat collects. As others have noted, when the temp in this area goes up, you need to turn on the fan, so it will push the hot air down through the slinky hose and out the bottom of the compartment.

The need to power up the fan is independent of which heat source is selected, so I'm not sure it is necessary to check each one independently. You need it even when propane is selected. The only question is what the ON and OFF temps should be. You don't want to select a temp so low that the fan comes ON if the TM is just sitting in the sun. On the other hand, you don't want to let the temp in the compartment rise too far before the fan starts. My uneducated guess would be that an ON temp around 90 degrees would be too low, but an ON temp of 100-110 degrees might be good, depending, of course, on where you usually camp.

A belt-and-suspenders approach might be to add a second fan. Control one manually with the inside switch. Control the other automatically with the thermal switch. At very least, that would solve the question that started this discussion - "OMG, I forgot to turn on the fan! Now what?"

That may be overly elaborate, but fans and switches are real cheap.

Again, I'm just noodling around with the idea.

Bill