ARB fridge temperature off

[rdonahe]

Expo folks,

I received my ARB 50 qt fridge yesterday and I'm afraid it isn't working right. I'll call ARB and the merchant I ordered it from later today during business hours but in the interim I thought I'd check to see what people here think.

There are two issues, one minor and one seemingly major:

Minor issue - when the fridge is plugged in to AC it makes a noticeable "electronic" type of hum. This is not the compressor sound I'm referring to. It makes the sound when the compressor is off, probably when it's on too but I can't hear it then. . The sound is there even if the fridge is plugged in but turned off. It gets louder when the fridge is turned on, and the volume of the sound seems to correlate with the display being on or off. When you check the temp setting and the display blinks on and off the volume of sound decreases when the display is off. It also decreases when the fridge lid is open and the interior light is on. I plan to use this fridge inside my vehicle where I also sometimes sleep. It's kind of annoying and actually seems quite prominent when there's no other noise. I've only run the fridge on AC so far so I don't know if it does the same on 12V. For those of you with the newer gen ARB, is this normal behavior?

Major issue - the temp that the fridge reports it is at is inaccurate and seemingly inconsistent. I'm using an electronic thermometer to validate the ARB reported temp and actual temps are seeming to run about 15 degrees warmer than the ARB reports. I know there could be a discrepancy based on where the probe is located but this is too wide. I can't spot where ARB has put the built in probe, I positioned mine in the middle of the fridge hanging off the basket grid in the air. This can't be normal behavior right?

Did I get a defective unit? I'm really disappointed right now after springing for the high end fridge. Any thoughts and experiences from other owners would be appreciated.

 

[goodtimes]

Have you checked to be sure your thermometer is accurate? That should be the first step. It's as simple as measuring the temperature of a pot of boiling water (approx 212*F), and the temperature of a bowl or glass of ice water (approaching 32*F).

I've never checked my ARB50, but it is reasonably close - certainly not 15* off.

 

[shogun]

I plan to use this fridge inside my vehicle where I also sometimes sleep. It's kind of annoying and actually seems quite prominent when there's no other noise.

You might want to amend that plan. I dont think you're gonna sleep with this thing. My fridge is not as noisy as the ARB and I can hear it from the RTT.

Yes, try running it from the vehicle 12v to see if it changes. Is the 120vac properly grounded outlet? Is there a freq/volt switch on the unit that might be in wrong position?

[/QUOTE]
Did I get a defective unit? I'm really disappointed right now after springing for the high end fridge. Any thoughts and experiences from other owners would be appreciated.[/QUOTE]

My research prior to purchase is that ARB is not "high end", rather a good, solid chevy/ford. Not hyundai/kia, but not ferrari/porsche.
Sorry I dont have any specific fix, keep us posted on the ARB fix.

 

[Sloan]

Call ARB and talk to Matt in tech support or better yet since you are in Seattle show him in person. Sometimes the temps are off and he can walk you through adjusting it.

 

[rdonahe]

Thanks for the responses so far.

In regards to calibrating my thermometer. I haven't officially done that but I use it all the time in cooking so I trust it right now a lot more than I trust the fridge temp. Also when the fridge is telling me the beer inside is 35F and I touch the bottle my many years of experience tell me that bottle is closer to the 50F that my thermometer reads than the 35F that the ARB tells me. I do plan to calibrate the thermometer though to make sure, probably tonight after work.

I plan to call ARB this morning shortly so hopefully will get to the bottom of it.

 

[ARBTECH]

Hi guys,
thought I would chime in here with some info on this.

Noise plugged into wall.
These fridges are DC native, when plugged into an AC circuit the power is converted in a rectifier built into the AC power supply. These make a noise whenever the fridge is plugged into AC power. The noise will not be present on DC power as the rectifier is not in use. It's not very loud, but in a quiet room can be heard. In this case the fridge is biased towards operating on DC power which creates a slight compromise on AC.

Inaccurate temp reading.
In this case the test procedure is a bit flawed. Air is a very good insulator so hanging a probe in the mid air will give a very erroneous reading. This is compounded by the lack of a circulation fan in the unit. The sensor in the fridge is located in the floor on the unit, fridge unloaded this will be the coldest point in the fridge and would result in a temp reading higher in the unit much greater than what the control circuit on the unit is seeing. Lastly, if the fridge has little thermal load (basically empty during the test) the fridge will cycle very quickly as the temp swings within the fridge will be rapid and inaccurate.

When we test a unit here we put a bucket with about 1.5 gallons of water into the fridge and set the temp to the desired level with the temp probe just above water level. This will work the fridge hard as it get's down to temp and settle into an accurate reading in 6-12 hours of run time. Anything less than this and the control circuit will still be "dialing in" on the desired temp. Overshooting both sides of the desired temp a little less at each cycle until the reading is +/- about 4 degree F.

From the description of the concerns I suspect there isn't anything wrong with this unit. Please check it a bit more thoroughly and if you find it is not operating as expected plan to bring the unit down so we can check it out at our shop.
Thanks,
Marc
ARB USA

 

[rdonahe]

I want to follow up on my post from earlier. Given that I'm local to ARB, and the gents there were amenable to me dropping in on them, I had them look at it and as Marc said in his post it sounds like it is operating normally.

I can verify that on DC power in my Jeep it is silent when the compressor is not running, so that more or less makes the noise a non-issue. I did have quite a few cans and bottles in the fridge during my temperature test so it wasn't empty, but other than that the behavior mirrored what ARB told me was expected. So at this point I'm going to summon a little patience and let it settle in over a few days and then see if the temps are in line with what I expect.

I do want to specifically thank Matt & Marc at ARB for being helpful on the phone and willing to have me drop in on them to take a look. That's great customer service in my book.

I'll post a follow up in a week or so.

 

[kevint]

Supercooling

I recently recieved a new ARB fridge and had an interesting experience in testing it. After returning home from a 1 week trip with the fridge, I wanted to see what temperature would freeze contents in the main compartment and not the top compartment. I had a six pack of water bottles on one side of the main compartment and a single bottle from my trip on the other side. In the top compartment I had some fruit. I started slowly lowering the temperature setting beginning at 30 deg-F. Every several hours I would remove the single bottle to check it. At about 25 deg-F I noticed that condensation on the sides of the fridge was frozen and shortly thereafter the single bottle had frozen. The six pack remained liquid.

I continued to drop the temp in the freezer a couple of degrees at a time and the six pack of bottle didn't freeze. I did some research and saw lots of discussion about testing the freezer more or less full so I filled it with forty 20oz water bottles. When I got the fridge down to a setting of 20 deg-F and still no frozen water, I began to wonder if there as a real problem with my fridge. However, the frozen condensation on the sides of the fridge and the fact that the single bottle froze between settings of 23 deg-F and 25 deg-F left me puzzled.

Then I remembered supercooling. I was taught about supercooling in high school and have seen some videos on the internet of the phenomena using bottled water. I took one of the bottles from the bottom of the fridge and smacked it on a countertop. It froze immediatedly. Then I put an ice cube in a bowl and poured another bottle of water on it and as the water hit the cube, it froze immediately building a pile of slush on the cube. These experiments mimicked some I had seen on YouTube in the past.

Anyway, this has no real relevance to overlanding but was quite cool so I thought I would share. I think what happend originally with the single bottle of water that froze is that after checking it at around the 25 deg-F setting, I dropped it back in the fridge and closed the lid. That drop probably initiated the freezing process. The original six pack of bottles I only inspected visually.

If you haven't seen this, here are a couple of videos from You Tube that duplicate what I observed.

http://www.youtube.com/watch?v=DpiUZI_3o8s

and
http://www.youtube.com/watch?v=Fot3m7kyLn4

 

[rdonahe]

Very cool accidental discovery kevint!

Since I'm the OP and I'm back in this thread I may as well update it. The ARB fridge after almost 2 years is great. I love it and no regrets. The temp gauge and actual temps (even after calibration) still don't match but I've gotten over it. I definitely recommend them.

 

[kevint]

Can you share anything about the calibration process and anything you've learned about getting the best from your fridge?

 

[rdonahe]

Can you share anything about the calibration process and anything you've learned about getting the best from your fridge?

The calibration process is to get an independent temperature reading and then modify the fridge's readout up or down to match.

So, more or less:
1. load up the fridge
2. put a glass of water with a trusted thermometer in the middle of the fridge
3. let sit for several hours, overnight preferable, to stabilize
4. compare trusted temp to fridge readout
5. adjust fridge readout per ARB instruction (sorry I don't recall the steps but they are available somewhere on Expo)

The only issue in my case was at step #5 there was not sufficient adjustment to get the temp to actually match. So my fridge still shows lower than actual temp on readout.

As far as getting the best from it there really isn't anything to worry about. Like any fridge it runs more efficiently the more you load it, more mass inside equates to less work. Other than that it's just use it and enjoy...