New ARB Freezer Fridge back to ARB for repairs...

[CarlsbadRover]

I went through the exercise to know just how low I could go before I'd have to be worried about bursting sodas, beer, etc. I found that I had to set mine to 26 degrees F to freeze water.

I wouldn't expect it to freeze water at exactly 32F. Most kitchen refridgerator/freezer's settings are somewhere around 36F and 0F (respectively). And while water technically freezes at 32F it can also exist as a liquid at this temp and things like purity of the water and elevation come into play too.

It doesn't bother me enough to contact ARB but if you do talk to them please post what you find out.

 

[cruiseroutfit]

A household freezer is set in the 0F (-17C) to 10F (-12C) range on standard operating setup, thus the same type of temperatures should be expected for your portable versions as well. Thus if you are taking ice-cream with you, 30F isn't going to cut it, real world losses prevent 100% heat transfer (through air in most situations within a portable unit) thus its pretty expected imo for your frige to be set at least 10 degrees (F) lower than freezing to actually obtain freezing items in your cooler. Different brand units may vary widely on similar situations, but that is 100% arbitrary imo and shouldn't be used to judge one unit from the next, rather it should be used as a baseline for the owner of said unit to decide what temperatures they use for various loading conditions. Your results may vary

 

[ARBTECH]

Hi Guys,
some good technical info on the operation of the thermostat assembly in the new fridge. This from the engineer who was in charge of the design. I asked for some clarification about the location of the sensor and the expected operation of this unit. I think it's interesting enough to share...Please see below.
Marc
ARBUSA



Hi Marc,

I hope that this helps. If I have maanged to confuse you further, please let me know and I will try again !!


The thermistor is located in the centre of the base of the fridge. It is located on the underside of the plastic base of the fridge.

This location was chosen because it gives a true reading of the temperature of the base of the fridge. The control system has an algorithm that relates this temperature to the temperature near the base of the fridge. By measuring the temperature of the base, it gives a good correlation to the temperature of the thermal load within the fridge. The air temperature within the fridge will fluctuate more than the temperature of the thermal mass within the fridge.

It should be noted that while the temperature reading is very close to the actual cabinet temperature, there will always be some fluctuation in temperature within the cabinet. A temperature display within 2-3°C (sorry can't do an easy °C to °F conversion) of the actual temperature of the bottom plastic liner is acceptable for the normal on/off cycle temperature variations.

There will always be a temperature variation between the top and bottom of the cabinet. This variation will depend on may factors including
How long the fridge has been running for
How the fridge is loaded (warm items, cool items, frozen items etc)
The target temperature of the fridge
Where in the on/off cycle the system is (ie has the compressor just stopped or is it about to start).

If a temperature probe is used to monitor the temperature within the fridge cabinet, it will only be measuring the air temperature. It will not give a good indication of the actual temperature of the thermal mass within the fridge. This is because the temperature of air changes more easily than an equivalent mass of solids or liquid. Therefore, a temperature reading taken in a full fridge will be more stable than one taken in an empty fridge (one filled with air).

It is also important that the fridge is allowed to cycle on and off a few times before an assessment is made about the temperature accuracy. You may have noticed that when you turn on an empty fridge, the temperature dips below the target temperature before it cycles off for the first time. We have set fridges to 32°F that have reached 23°F before they cycle off for the first time. After the first cycle, the temperature variation stabilises to about +/-2°C. This dip does not occur when the same test is conducted with a loaded fridge. In this case, the temperature takes longer to reach the target temperature (as it cools the thermal mass) but it does not dip significantly below the target temperature. I hope that this highlights the different behaviours of the fridge when it is full vs empty. While these behaviours are different, they are both acceptable.

On our previous fridge (sawafuji 40L), the temperature is measured using the refrigeration lines. If you look inside the rear cover of a 40L fridge, you will see a small soldered connection where one of the copper refrigeration lines leaves the foamed cabinet. This temperature sensor is measuring the temperature of the refrigerant pipe and not the cabinet temperature. For this reason, the system is slow to react to any changes in cabinet temperature (for example leaving the lid open of filling the fridge will a warm load). This temperature sensor can also be affected by ambient conditions outside the cooling cabinet.


Regards

James Luke

Product Development Engineer

 

[cruiseroutfit]

Excellent tech Marc, thanks!

 

[mrchips]

I just got a new ARB, NWOODS did you plug it into the power outlet on the RUBICON dash or did you run a separate plug to the back . Thanks

 

[roscoFJ73]

Good bit of fridge tech and probably applicable to most brands.
I suspected much of that was happening but its good to to have it confirmed by someone who knows what they are talking about:ylsmoke:

 

[off-roader]

Wow, didn't realize my post was still alive even after I stopped posting.:sombrero:

Marc, thanks again for all the great help. As I noted earlier, I had heard about the great support ARB offered and you've definitely delivered!

Kudos:smiley_drive:

 

[CarlsbadRover]

Issue with the cam lock hinge?

I read somewhere about a problem with the hinge on the cam lock...something about how it's prone to breaking and ARB is releasing a fix? ARBTECH can you share any info on this?

 

[off-roader]

Carlsbad Rover, you may want to ask that in a different thread?

Just makes sense to keep things on one topic and not roving all over the place.

 

[cruiseroutfit]

I read somewhere about a problem with the hinge on the cam lock...something about how it's prone to breaking and ARB is releasing a fix? ARBTECH can you share any info on this?

Fix is complete and released, you can see a picture here

Its honestly a rare problem but its been addressed and if/when you have a problem the new fix is available

 

[ARBTECH]

Updated fridge latches are in stock if needed. The problem only affected the first batch we saw and the trouble came if the latch was over exerted when opening. The result is an inverted latch that opens past the built in stops. Most users have not had a problem as they understand the latch operation. We saw the problem most in fridges being used at shows actually where everybody was trying them out. Regardless, if you have the early latch and it acts up call and ask for the tech department and well sort it out.
Marc

 

[off-roader]

The problem only affected the first batch we saw and the trouble came if the latch was over exerted when opening. The result is an inverted latch that opens past the built in stops. Most users have not had a problem as they understand the latch operation. We saw the problem most in fridges being used at shows actually where everybody was trying them out. Regardless, if you have the early latch and it acts up call and ask for the tech department and well sort it out.
Marc

Marc,

I believe my fridge may have been one of the early units since it was (IIRC) in the first shipment to the US (back in Feb?).

My thinking is while I'm comfortable with knowing the operation of the latch mechanism, I'm concerned that during a trip a friend might try and operate it and damage it then which brings up my other questions...

1) Are there any visual cues to tell if the latch mechanism is the original potentially problematic one? (pic of old next to new maybe?)

2) If the latch malfunctions, how difficult will it be to secure the lid especially in an 'rough' off road situation? How easy is it for the lid to bounce open?

3) Is it recommended that once I've identified that I do have a potentially problematic latch to replace it before a big trip like the one I'm planning in Oct to the Mojave Road/Trail where having a refrigerator would be very beneficial.

TIA

 

[cruiseroutfit]

New:

Old:

I wouldn't replace it unless it proves to be a problem, even it gets inverted you just pop it back into place. I've never seen one break nor seen a broken one firsthand but my impression is it likely breaks when you try to re-invert it?

 

[Crikeymike]

2) If the latch malfunctions, how difficult will it be to secure the lid especially in an 'rough' off road situation? How easy is it for the lid to bounce open?

You could use a tie down strap, but I doubt you'll ever have that problem that you'll need a fix for.

 

[CarlsbadRover]

Thanks Marc!

Sorry if I hijacked/"tangented" this thread