Maybe this will keep my fridge cool?

[austinado16]

Here's a shot of the switch installation.

There is a noticeable "soft breeze" out the upper louvers with the fan running and I figure at just under 8CFM, it's probably changing the entire air in the cabinet about 2-3 times per minute.

Expense: Fan and switch came to $17.22 with tax.  

Addition parts: 2 female spade connectors and 2 16ga butt splices, 6 small zip-ties, and 3 plastic wiring holders with screws.

Time invested:  Maybe 30min including taking the louvers of and putting them back on again.

[austinado16]

Well, day 3 of fridge testing is about over and the temp peaked at 40.3*F, about 7.5*F cooler than the highs of the last 2 days.  This with food on board, temp setting all the way to "9" and the fan running for the last 4hrs.

Still not great because this was with the door remaining closed all day.  Had it been opened for lunch and later for snacks (I opened it in the morning to put the cold test food inside) It would probably be up another 3-5 degrees.

Any suggestions on how to improve this are certainly welcome!

[AustinBoston]

Well, day 3 of fridge testing is about over and the temp peaked at 40.3*F, about 7.5*F cooler than the highs of the last 2 days.  This with food on board, temp setting all the way to "9" and the fan running for the last 4hrs.

Still not great because this was with the door remaining closed all day.  Had it been opened for lunch and later for snacks (I opened it in the morning to put the cold test food inside) It would probably be up another 3-5 degrees.

Any suggestions on how to improve this are certainly welcome!

One thing I heard of someone else doing was putting a small shade awning over the fridge on the outside.  If your fridge is on the sunny side of the pop-up, providing it with shade could help.  Just make sure there is plenty of room for the warm air you just blew out with the fan to clear away freely.

Another option is to make sure you always camp with the back of the fridge facing north.

You could get an a/c for your pop-up, and install a duct from the a/c output to the base of the fridge, cooling the fins with a/c air.

Looking at your pics, it looks like there may be significant air gaps between the fridge and the Reflectix.  If there is, try to find styrofoam or other foam insulation that will completely fill that gap.  The thin foam that is used under vinyl siding may work; you could layer it until you have the best fill possible.

I think these are all long shots, but they are all (ok, all but one) cheaper than a new fridge.

Austin

[austinado16]

Good suggestions.

For this test, the fridge louvers were in the shade and on the north side, so this is probably as cold as it's gonna make......unfortunately.

You're right about the reflectix not filling in completely. Actually, it did on the top and on the left side in that one photo, but on the right there was about a 1" gap.  I filled that in with some ceramic wool insulation that I happened to have.  So, the fridge is packed in solid right now.

It may just be that it's "damaged" internally either from age and a million hours of run time, or from being run while not level.....or both.  Bottom line is, it's just not as efficient as it should be and that's too bad.

[mykwalker1]

Well, day 3 of fridge testing is about over and the temp peaked at 40.3*F, about 7.5*F cooler than the highs of the last 2 days.  This with food on board, temp setting all the way to "9" and the fan running for the last 4hrs.

Still not great because this was with the door remaining closed all day.  Had it been opened for lunch and later for snacks (I opened it in the morning to put the cold test food inside) It would probably be up another 3-5 degrees.

Any suggestions on how to improve this are certainly welcome!

What are you using to take the temps?  Is it just ambiant air temp or is it the temperature of the product inside?   The reason that I ask is that when I worked in the food service industry we always put our probes in a gel in the fridge.  That told us more accurately what the temp was for the food inside and aleiviated the high spikes that you would see with the ambiant temps.  :eyecrazy:

I don't think opening the door for 5 minutes at lunch a few (3) to pull out the food and a couple (2) to replace the food that wasn't used and 2 minutes or so at a later snack time would not affect the temperature of the food more than .5 of a degree -- but would affect the ambiant temp drastically (probably a 10 degree swing) and would be corrected within 15 minutes of a closed door situation.

Maybe your temps aren't that bad when looking at it from the standpoint of what the food temps are throughout the day.

What was the outside temps on day three?  Was there any change from the day before?

[austinado16]

These are excellent points!  In fact, I went out last night and grabbed a big nectarine out of the fridge just to see how it was doing......it was very nice-n-cold.  There are some yogurts in there and I was going to poke my digital temp probe into one of them (which is attached to my $350 Tectronics digital volt/ohm meter).

Right now I've tried 3 different temp sensors.  One is the digital fridge thermometer that I bought at the local RV place.  It has a sensor that's stuck to the inside wall of the fridge about midway back and midway up the wall.  As you say.......it's extremely sensative.  Open the door and bam, the temp starts to creep up almost instantly.  Of course I know the food isn't doing that.  The other temp sensor is the remote unit that came with my Acu-Rite weather station.  That reads the same as the fridge thermometer.  I also put the probe from my Tectronics meter in there and it agreed with the other 2....as far as ambiant temp goes.  The final temp sensor is one of those metal spike style appliance thermometers that are mechanical and you can adjust the nut on the back to make them accurate (at least at freezing).  So, it's calibrated to 32*F and it actually reads lower than the other thermometer, and more stable.....as if it were the food.

Day 4 and air temps peaked today at 96*F in the shade, inside the pup was well over 100*F and the fridge is showing 43.6*F inside, but the ice cubes in the little freezer are still frozen.

Guess I'll go poke a hole in yogurt cup and see what's goin' on.

Thanks for the tip!

Okay: yogurt temp test.  It was actually 37*F inside the yogurt when I first put the temp probe in.  Meanwhile the fridge thermometer was reading 43 and change.  So, I feel pretty good about this, especially after the 96*F day we've had today.

[austinado16]

Day 7 and time to bring the fridge testing to a close.

Following Day 4 with 96*F weather, on Day 5 we had a blistering day of 105*F.  Fridge air temps inside maxed out at 51.8*F and cooled to the low 40's during the night.

Day 6 came and went with outside temps back in the 80's and the more normal fridge temps in the mid 30's in the morning and low 40's in the late afternoon.  Cooling down to 35*F last night.

One final food temp test this morning showed the yogurt was 30*F inside, but not frozen.

The fridge cube fan ran for 5 days and was still running this morning...and that's after 5 days to and from the Grand Canyon, 2 days to Kings Canyon, and all the other pre-cooling and other testing I've done with the cube fan running.  Pretty good on the same set of D-cells.

So for what it's worth, here's what I learned:
1) It's important to have food (and probably ice cubes in the ice cube tray) in the fridge when doing temp tests.
2) It's important to take the temp of the food because it is typically 5 or more degrees below the temp of the ambient air in fridge.
3) Painting the fridge coils/fins may not do anything to help cooling.
4) Redoing all the insulation with Reflectix may only help marginally.
5) Installing an external fan to help pull or push air out of the rear fridge cabinet does have some benefit.

Mods for the future?
1) I noticed during hot days that the face of the refrigerator door was getting really warm.  Basically the whole PUP inside was really warm.  I'm wondering if there can be some heat transfer through the front door.  I've got a spare fridge and if it looks like the doors come apart easily, I might take a quick peek inside to see what they have for insulation.  If there's room to stick in a layer of Reflectix, I probably will.

2) Keep my eye out for a 12v fan that uses less than the 1.5amps my radioshack one uses, or that moves more than 7.7cfm for the same amps.

[AustinBoston]

Day 7 and time to bring the fridge testing to a close.

It would be interesting to see tabulated into a list the various fridge/outside temperature readings you have made.

Austin

[austinado16]

It would be interesting to see tabulated into a list the various fridge/outside temperature readings you have made.

Austin

I think it would be more interesting if I'd put more "controls" in place before and during the test, so I could have more results where I could honestly say, "This resulted in that."

But, the temps last week and this weekend were all over the place from lows at night to 53*F and highs during the day up to 105*F.  That helped the fridge temps swing all over the place too.

But the pattern I saw was that nightime air temps 65*F and lower would allow the fridge to cool into the high 20's if I left the dial on 9 or higher.  Then during the day, no matter where the fridge was at night, or what the dial was set to, the fridge temps ran at about 40*F until the outside air temps got up into the 90's and above. Then it was mid to high 40's and for a brief time, as much as 52*F.

The first couple of days were inaccurate because there was no food in the fridge.  Adding food and letting it make ice cubes in the little freezer box brought the air temp of the fridge down almost 7 degrees.

So:

Night time outdoor temps(min)..........Night time fridge temps(min)
             53-65*F ...................................................27-33*F

Day time outdoor temps(max)...........Day time fridge temps(max)
             85-105*F...................................................40-53*F