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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: geomm on August 07, 2013, 08:08:27 pm

Title: Fridge/Freezer temps
Post by: geomm on August 07, 2013, 08:08:27 pm
I have a Dometic RM7130 side-by-side unit. When I hooked it up to shore power for the first time last month it took about a day before it started making ice cubes. Then -- I started noticing frost forming within a day after, and I had the setting on 4 of 5. A couple days later the frost was building up fairly heavy on the aluminum fins in the fridge section, and so I backed it off to setting 3. Frost continued to build so went to 2.

Then I went and bought a thermometer for fridge/freezers, and with it in there over a day, swapping it side to side I was at 32 on the fridge and -10 on the freezer (again, at setting 2).

So now with the setting at its lowest of 1, the frost is gone from the fridge side (still some light frost on the freezer side), and my temps are 42 in the fridge, and -2 in the freezer.

Having never actually measured temps in a brix and sticks appliance, are these numbers good ones? I'm mostly wondering about the 42 degrees in the fridge.

The ambient temps here in Southern California have ranged from the high of about 90-92 and evening lows dropping to about 58-60  -- lately.

It would appear -- I have a lot of reserve cooling capability if I needed it in a hotter climate.

Be careful out there,

Michael
Title: Re: Fridge/Freezer temps
Post by: Michelle on August 07, 2013, 08:22:33 pm

Having never actually measured temps in a brix and sticks appliance, are these numbers good ones? I'm mostly wondering about the 42 degrees in the fridge.

The "Danger Zone" for fresh food is 40-140 F (that's the temp at which bacteria will grow and thrive, and perishable food should be in this temp range for no more than 4 hours total or you should not eat it). 

FDA recommends fridge below 40F and freezer below 0F.  The default setting on our home fridge is 37F and -1 in the freezer.  We keep our coach fridge in the 35-38F range; I don't think we've ever measured the freezer.

Hope that helps!

Michelle
Title: Re: Fridge/Freezer temps
Post by: wolfe10 on August 07, 2013, 08:29:47 pm
Michael,

Where is your thermistor-- how high/low and on which refrigerator fin.

Moving the thermistor down (colder location) raises refrigerator temperature which might give you more control by using a higher setting.

Also moving it inboard on the fins does the same thing, as inboard fins are colder, so it turns off the cooling unit sooner.

Brett
Title: Re: Fridge/Freezer temps
Post by: Tim Fiedler on August 07, 2013, 08:30:07 pm
my residential was set at 40' for the fridge and 0' on the freezer when it came from the factory - works for me just fine as is
Title: Re: Fridge/Freezer temps
Post by: John S on August 07, 2013, 08:32:22 pm
My new residential fridge is set at 38 and -2
Title: Re: Fridge/Freezer temps
Post by: Dave M (RIP) on August 07, 2013, 08:55:56 pm
 ;D  Ain't em home refrigs wonderful ?  I am the happiest guy around refrig 36 & 2 Freezer, keeps my ice cream just right,  question, why did I put it off so long ?  ???
Title: Re: Fridge/Freezer temps
Post by: Caflashbob on August 07, 2013, 09:05:36 pm
Michael,

Where is your thermistor-- how high/low and on which refrigerator fin.

Moving the thermistor down (colder location) raises refrigerator temperature which might give you more control by using a higher setting.

Also moving it inboard on the fins does the same thing, as inboard fins are colder, so it turns off the cooling unit sooner.

Brett

Good info.  Move the thermistor to adjust temps.  Thanks
Title: Re: Fridge/Freezer temps
Post by: geomm on August 07, 2013, 10:33:07 pm
Brett,

The thermistor was in the upper right corner -- right to the top. So I moved it down about 8 inches (can't move it inboard because of the width of the slide-on bracket) and I bumped the setting to 2 -- we shall see tomorrow if that lowers the temp to a more ideal 36-37 degrees.

Thanks. I never would have even looked for the sensor unless you brought it up.
Title: Re: Fridge/Freezer temps
Post by: John S on August 08, 2013, 06:32:03 am
On my propane fridge i used a setting of three.
Title: Re: Fridge/Freezer temps
Post by: Dave Head on August 08, 2013, 07:47:55 am
I found mine laying in the drip tray. Putting it on a fin helped immensely.
Title: Re: Fridge/Freezer temps
Post by: Old Hippie on August 08, 2013, 12:28:10 pm
So just to understand; the thermister can be raised or lowered on the 2nd fin (from the right) so for more cooling place the thermistor higher on the fin. Would the last fin be even warmer and if you put the thermistor on that one you could have more cooling?
I replaced the thermisor on my Norcold side by side and the freezer went to 11 and the fridge only went to 44. I want more cooling in the fridge.
I also added a fan set up in the middle of the fins which helped with frost but not much for cooling.
thanks
OH
Title: Re: Fridge/Freezer temps
Post by: Barry & Cindy on August 08, 2013, 05:26:06 pm
Refrigerators don't have adjustable cooling. They cool at a constant temp, but the inside of the box will get colder over time by running longer. If thermostat setting is changed or the temperature sensor (thermistor) is relocated, cooling will run shorter or longer based on the change. When heat is being applied, a portion of the cold gas absorbs heat from freezer box, on the way to the refrigerator box, before it is recycled for reheating.

Some have put many (4-6 muffin) fans that blow against or away from fridge fins to keep moist cold air moving, which can reduce frost build-up and helps to better even out temps inside fridge. At any one moment, fridge temps can vary 20 degrees between fins and bottom area.
Title: Re: Fridge/Freezer temps
Post by: PatC on August 08, 2013, 06:01:31 pm
I got one of these Dometic Norcold Refrigerator Fan for RV 12 Volt | eBay (http://www.ebay.com/itm/DOMETIC-NORCOLD-REFRIGERATOR-FAN-FOR-RV-12-VOLT-/251249747796?pt=Motors_RV_Trailer_Camper_Parts_Accessories&hash=item3a7fa6e754&vxp=mtr).  Works really good.
Title: Re: Fridge/Freezer temps
Post by: George Hatfield on August 08, 2013, 06:58:48 pm
Our Dometic 1492 side by side typically runs 34-38 on the refrigerator side and -1 to 4 on the freezer side.  Typically we run on setting 3 out of 5.  We too had frost problems until I put in the internal fans shown below, which we got from an eBay supplier.  I ganged three together.  I also have roof fans, which I have posted on previously.  We normally only run them in hot weather (>85).  They seem to help a bit, but not dramatically.