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Old 07-12-2020, 06:49 PM   #1
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2016 AI; Adding a refrigerator vent fan for better cooling

Like most people, we had issues in our new to us AI keeping the refer temp acceptable when the freezer was running, and it was warm out. Last trip out it was reading Approx. 45F most of the time. Since ideally it should be 40F or below, that is a bit of an issue. After some research on here and elsewhere the problem was most likely lack of air movement over the coils. The air that was moving was to warm rising from the freezer coils since the freezer was just below it. The freezer was below 10F most of the time. Note: it was in the mid 90’s most of the day. When I would turn off the freezer for a few hours, the fridge temp went down…. So, that seemed to be the culprit.

Plan: Install a fan to draft more air over the coils and bring the temp down. Remove the 120V plug. Put in a push button on/off switch.

I picked up a Titan dual 12v fan with controller and thermostat off Amazon. I used the smaller 90mm. There are cheaper ways to do this, but it had the pre-wired control for speed, or time and auto that went off the included thermostat. At max it uses 0.5A/6W. So, it could run if we were on batteries with out a huge drain. And it is easy enough to turn it off.

The fridge weighs 48 lbs, which was too much for me, so the wife pulled it out 😊. Here’s where we ran into the first issue. The positive and negative wires are connected to the back by female Bayonet connectors. The neg popped off easily. The Positive however was spliced in with another connector that was spliced to a thin wire elsewhere on the fridge (optional lighting kit?). Anyway, there is not enough wire on the positive to pop the fridge out further to examine things, so I snipped it about 12” from the fridge (yes, the power was off). This would allow for easily re-connection later with bayonet connectors. Here is a pic of the connectors and the wiring diagram on top of the fridge.
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There was no 120V plug. The freezer did appear to have one but didn’t see it plugged in. Once the fridge was out and out of the way on a moving pad we got a better look behind it. Be careful the bottom has sharp edges that could/will scratch anything you put it on.
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Up at the top it was all open with an opening above the bathroom. Not good for drafting air.
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I took heavy duty aluminum foil and aluminum tape and closed it all in, creating a smooth airway to help maximize air draw and flow.
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I then spliced in the new vent fan wires to the pos/neg wires and secured them out of the way. After that I fixed the thermostat probe to the center area of the overhead directly above the vent fans.

The wife put the fridge back in. I put screws back in and ran the wires to the control head for the fan behind the vent. I am not sure if I am going to drill holes and mount it in the pantry or not. There is a lot of value in being able to see it is on. I mounted it upside down to keep the wires clear of the pantry door. I used reusable nano grip tape. Strong bond and removes easily with out damage.
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We didn't put the power disconnect switch in. May do that another time. Here is the reason we want one is this. You have to keep the AI on shore power or at least charge it once every 10 days or the parasitic draws kill the batteries. So you can't use the battery disconnect switch (since there are draws before that) ... it has to be on to charge. Even if you turn the fridge off, the LED light remains on if the door is open (the way they wired it direct to the 12v+ lead). So you can't leave the door open if the fridge is off to prevent the musty smell with out the light being on.

We are taking it out this weekend so we will see if it is any better cooling. It is supposed to be in the 90’s again.
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Old 07-12-2020, 10:07 PM   #2
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The fan will pull air from anywhere it can get it. Mounted that way, a lot of the air it moves will come in from the louvers around it and just be recirculated. It would help to build some sort of cardboard duct around the fan that leads back to the rear of the unit. That way, more of the air it moves will be beneficial.
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Old 07-14-2020, 08:14 AM   #3
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So as I understand it, the fridge can run off 12v. If I “unplug” the normal plug to the outlet, will that force the fridge to only run on 12v?

Running it on 12v seems more efficient than converting to 120. No big deal to plug it in when on shore power.
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Old 07-14-2020, 08:59 AM   #4
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Originally Posted by Heckler56 View Post
So as I understand it, the fridge can run off 12v. If I “unplug” the normal plug to the outlet, will that force the fridge to only run on 12v?

Running it on 12v seems more efficient than converting to 120. No big deal to plug it in when on shore power.
Right.

I run everything on 12v when I use my Goal Zero for that reason. Voltage conversions are lossy.
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Old 07-14-2020, 09:12 AM   #5
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Maybe a silly question: is this a 12v danfoss-compressor fridge or an ammonia-absorption fridge? Thanks!
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Old 07-14-2020, 09:14 AM   #6
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Maybe a silly question: is this a 12v danfoss-compressor fridge or an ammonia-absorption fridge? Thanks!
It is a compressor fridge. Listen closely and you can hear the compressor.
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Old 07-14-2020, 09:54 AM   #7
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Novacool suggests 30 sq. inches top and bottom for my model and 60 sq. inches top and bottom for larger models like in your GT. Airstream's venting is very poor and can fall way short.


My smaller 3.1 cf Novacool was installed with no lower ventilation and the top had to vent around the rear of the microwave, over the top, and out the front microwave grill. The area behind my fridge was also lacking in insulation allowing heat transfer to the area from the outer skin. So I added spray foam & reflectix. I also opened up the area below my fridge to improve intake and decided to supplement the top exhaust by adding a fan, but in a different manner than yours.


Without an area to add a muffin fan like you did, and precious little wall space to add a cutout, I had to get creative. I ended up installing an ultra small squirrel-cage fan (16CFM) with a 1-1/2 inch round output. I mounted the fan high and inside the area behind the fridge wired to a button thermostat (on at 100/ off at 85 degrees) and an lighted on/off switch. Then I ran a flexible tube from the fan and out through a small 1-1/2" circular grill on a wall 90 degrees away from any intake.


The fan never comes on while driving, but when sitting with direct sun on that side of the van in Summer heat, it occassionally turns on. Since it is drawing in cooler air from the living area inside the van, it will quickly cool down that area by 10-15 degrees. However, it will run until the sun is off that side in order to lower the temp below the thermostats 85 degree cut off.


If I do nothing and leave the fan off, then the normal convertion flow works (compromised as it is by the microwave sitting right above the fridge). Pics below were taken with the microwave removed.
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Old 07-14-2020, 10:42 AM   #8
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Quote:
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It is a compressor fridge. Listen closely and you can hear the compressor.

Thanks! Don’t own an Interstate (yet?), just wanted to understand because poor ventilation / cooling in back is a common problem for ammonia-absorption fridges.
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Old 07-18-2020, 09:18 PM   #9
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Good results so far

Quote:
Originally Posted by Pahaska View Post
The fan will pull air from anywhere it can get it. Mounted that way, a lot of the air it moves will come in from the louvers around it and just be recirculated. It would help to build some sort of cardboard duct around the fan that leads back to the rear of the unit. That way, more of the air it moves will be beneficial.
John.

Good point. We are camping in it this weekend and have seen 38F consistently. Highest has been 40F after being in and out of it constantly. The fan is on high though, but still temps are lower then we have ever seen and it is 90F outside with the A/C at the same temp it was the last time we were camping.

I think an easier way to tweak some more air flow from the fans is to split them apart and mount them directly to each grate. That way the fans will be far more effective for air flow in the right direction. The whole upper chamber will act as the duct, which was the original goal. We should see the same airflow/temp improvement but on lower fan settings (lower watt usage). I think I am going to put a remote thermometer in the back to monitor the temps for a while. Probably change out the thermistor on the fans temp probe to a higher temp one. Read it was for 68F. Will do some testing to see what the max temp is for it to kick on and still maintain adequate airflow across the coils.
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Old 11-29-2020, 02:41 PM   #10
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A bit more tweaking

Taking Pahaska's input I split the 2 fans apart (easy to do with the set I go). Put some double sided tape on the top and bottom of each and wedged them in nicely on the back side middle of each vent cut outs. Sealed the edges and any other leakage with aluminum duct tape (thin metal tape). The air flow increased significantly and now the refer stays very cold! We have to keep an eye on it no since if it is set to high for the current temp, it will freeze stuff!

The "auto" function works great. It kicks on the fan when it starts to get warm behind the fridge. definitely worth the $ & time. It will stay cold now on even the hottest day in FL.

New separated fan location:
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Sealed up:
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Turned on and venting:
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Old 11-29-2020, 04:24 PM   #11
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Our lounge version has the little teeny Norcold fridge/freezer, which works but doesn't keep the freezer very cold. After we upgrade our batteries, I will have to look into the ventilation situation there as well - maybe it just needs better airflow, which could also improve the efficiency of that little refer.
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Old 11-29-2020, 04:46 PM   #12
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Quote:
Originally Posted by Rocinante View Post
Our lounge version has the little teeny Norcold fridge/freezer, which works but doesn't keep the freezer very cold. After we upgrade our batteries, I will have to look into the ventilation situation there as well - maybe it just needs better airflow, which could also improve the efficiency of that little refer.
The venting is a disgrace! My first step was to replace the blank board at floor level with a louvered marine vent to provide a low place for cooling air to get in the cabinet. The only other place is around the microwave. There are a lot of photos I posted on this fix and also upgrading the vent at the top.
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Old 11-29-2020, 05:05 PM   #13
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Quote:
Originally Posted by Rocinante View Post
Our lounge version has the little teeny Norcold fridge/freezer, which works but doesn't keep the freezer very cold. After we upgrade our batteries, I will have to look into the ventilation situation there as well - maybe it just needs better airflow, which could also improve the efficiency of that little refer.
Pahaska is correct, The ventilation/airflow is nonexistent and you need to focus on this first. This is the cheapest/easiest way to boost efficiency and save energy (amp hrs since the compressor won't have to work so hard/long)! My mod cost $75 for the fan https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
and some aluminum tape (which I had but cost about $15. I used maybe $1.50 worth).
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