Any Tips to Improve 12v Compressor-Driven Refrigerator (Isotherm 65) Performance?

manyman297

The 12v fridge is amazing compared to our old absorption fridge but when the temps hit the high 80s into the 90s it starts to struggle. I think a lot of this is due to the interior temperature of the trailer and not running the AC when boon docking. Aside from keeping the interior cabin cooler, I've read that replacing the stock fan with a larger or "better" one can help? Any ideas?

Dutch061

What exactly does "when the temps hit the high 80s into the 90s it starts to struggle" mean? Struggle is pretty subjective and is pretty difficult in my book to provide you with any kind of an intelligent response. 

This I can say, on our 2020 400 BDL, I have zero issues with the compressor refrigerator. It has been in the low to mid 90's in NC and I have had it running for nearly 30 days and monitor it with a Govee Temperature and humidity sensor tied to the rack in the front center. I did set the knob a little higher today towards the middle (between 3 and 4) while I had the door opened for a few minutes loading it for a multi day trip in the morning. The warmest I saw today was 41.0 degrees. 

My average temperature for the last 3 weeks is right at 40 degrees and includes lots of days either sitting in the sun or boondocking. Now I already can hear everyone shouting that 40 degrees is not cold enough but I would submit back to you that having 3 other RV's with absorption refrigerators (including a TAB 320-S) before this 12 volt compressor refrigerator that to maintain an average temperature of 40 with a Maximum of less than 42 degrees during this kind of heat is simply not possible with an absorption refrigerator. If you were to monitor the performance of an absorption refrigerator in similar temperatures, you would likely never use it for food in the heat of the summer again

Since I have also upgrade the batteries to lithium, I have thought about pulling the refrigerator out and removing the battery compartment vent hose. This would allow me to install a fan on that vent to move the warm air from behind the refrigerator compartment to the outside rather than forcing it to move around inside the camper. This may be a modification I do over the winter. 

I believe that moving that air outside rather than keeping it inside would certainly reduce the amount of time per hour that the compressor runs since the refrigerator would no longer be sitting in a pool of hot air making sure to keep it warm. 

Brad

manyman297

By struggle I mean getting above 40 degrees. I’ve been using a cheap fridge thermometer conveniently labeled in Celsius…but when converted it’s probably as high as 45 Fahrenheit at some times. 

It sounds like exhausting the heat out of the camper is the best move. Don’t have lithium so I’d have to find an alternate route. 

Dutch061

I wonder if anything changed with the refrigerator or the cabinetry area between 20 and 21? I haven't seen a 21 personally, so I am not able to comment further. 

I am pretty sure that moving the hot air from around the refrigerator will not only reduce the cycling time but also will improve efficiency by eliminating the hot soak condition all of the time. 

Brad

johnfconway

Anything that can be done to keep cabin temperature below 95 degrees pretty much guarantees safe performance from Isotherm 2-way fridges. Tweeking ventilation around the fridge is likely to pay off. In our case, removing 3-way and replacing it with similarly sized 2-way, but leaving the two large outside vents intact, made a difference in temperature around the fridge itself.

Here is link to measured "test" of new refrigerator. https://tab-rv.vanillacommunity.com/discussion/13775/norcold-n3104-replaced-with-isotherm-freeline-115-in-t-b-400#latest

Note that a day later, we were beyond 95 degree cabin temperature and all bets were off. We always carry a 3 gallon Igloo iced water jug. That helps prevent a wall of 100 degree cabin heat displacing 41 degree refrigerator air in (probably) 5 seconds!