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Old 08-13-2007, 06:20 PM   #15
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Thanks - I really have no idea what is normal, just trying to help billberk.

FYI, those temp readings were taken with an empty fridge set at it's max setting, working on AC, with Spiffy parked in direct sunlight. Pictures of the fridge install are found in my photo galley. No fans installed - only a thermal process at work . ..

grantb4, when I read the installation manual for my NorCold prior to installation, they had rigid requirements with regard to the area of intake (else the warranty would be void). That fan from Snyder's RV is very intake restrictive and clearly out of specs from Norcold. Can I assume that if you install it that you will have to use it full time?

If so, that fan looks like the one in my computer case. How much battery is needed to run it per hour?
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Old 08-13-2007, 06:41 PM   #16
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I think you would have to run it pretty much all the time. Our current fan runs most of the time except when it's cold out. Hopefully the Synder one is quieter, but frankly right now that's the least of my concerns.

Anybody know of a temperature monitoring station that records hourly or something like that? I use one that accumulates a min and max, but I'd like to track the temps in at least 3 places with more detail than that.
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Old 08-13-2007, 07:12 PM   #17
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In regards to the fan from Snyders. I installed one a few weeks ago in my 1978 Ambassador. The frig vent runs up the curbside wall. After the frig was cool I put my hand on the vent wall. It was noticably hot which leads me to believe that the fan system really pulls the air through there helping it cool. Just an observation...
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Old 08-13-2007, 07:34 PM   #18
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tlavergne, I would guess just the opposite.

If the air is being moved efficiently, wouldn't that movement keep things, including the flume, from getting that hot?

The thermal process is dependant on the lack of restriction on the intake and the management of restriction at the place of heat transfer to the exhaust. The more cubic inches of space that must be heated, and kept hot, above the heat plates, the hotter that portion of the system must become to keep the thermal process working.

That said, you want the exhaust scoop to be warm so it doesn't cool the air down, else it will cause that cooler air to sink again, and not exit out the exhaust. If that happens, then the thermal process breaks down. The more it happens, the less efficient the system.

I kind of cheat: I had a metal scoop made and have it insulated on the outside with bubble wrap, limiting the out-of-scoop effect.

At least in my thinking . . . for what it's worth.
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Old 08-13-2007, 08:42 PM   #19
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It's hard to tell which direction the Synder moves the air. It almost looks to me like it pulls air down from the top, but it's hard to tell from the picture. Anyone have any idea? I think the proof would be how does the fridge operate (without compromising it's life).
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Old 08-13-2007, 08:58 PM   #20
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thermistor....

How cold should my fridge get? The answer is it depends --- on the ambient temperature, but generally the fridge will operate at 38-42 degrees Fahrenheit (4-6 degrees Celsius). This represents a 40-degree drop from typical ambient temperature, with the temperature control set at 3. A refrigerator in an older coach will lose its efficiency as it ages and it may not be able to maintain this temperature without adjusting to 4 or 5. The freezer section is designed to be 30 degrees (15 degrees Celsius) less than the fridge temperature.

On most side-by-side Dometic fridges and some two-door units, you can also move the thermistor (a white unit with two fine wires going to it) that is attached to the fins in the back of the inside of the fridge. With the fridge set at 3 and normal operating temperatures of 70-75 degrees outside, measure the inside temperature using a fridge thermometer. If the fridge is too warm move the thermistor upwards on the fin (Up is Colder like “Up North”). This will calibrate the temperature and maintain the proper temperature on 3. Hopefully these items make it easier for you to live with you Dometic refrigerator.
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Old 08-13-2007, 09:34 PM   #21
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Hey Dwight---careful with that "colder is up, like up North". It's above zero here today. Marked it on the calendar. To many days like this and the snow will begin to melt .
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Old 08-13-2007, 10:45 PM   #22
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Quote:
Originally Posted by Dwight
If the fridge is too warm move the thermistor upwards on the fin (Up is Colder like “Up North”). This will calibrate the temperature and maintain the proper temperature on 3. Hopefully these items make it easier for you to live with you Dometic refrigerator.
I'd like to know where it says that this makes a difference. Has anyone done a verifiable test? I know that hot air rises, but moving the thermistor on the fin is not really measuring the air, it's the metal fin temp and I'd be surprised if there was a temperature gradient of much difference as long as you are on the edge. Now moving the thermistor off the fin might do something, but it might overwork the fridge too. And not only that, the freezer is at the top so you'd be moving the thermister closer to the coldest part of the fridge. Seems like old wives tale stuff to me, but I'm eager to be proved wrong.

I did a Google search for "dometic thermistor fin" (without the quotes) and found a couple of useful links at Rv.net: dometic thermistor fin - Google Search . Some people had good experience with moving the thermistor until it poked out from the palstic clip and the fin, thus exposing it to the air. That caused the fridge to work harder but cool more. Also and interior fan helped some. Here is also a link to Dometic service manuals: Service Documents I will examine these further.
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Old 08-13-2007, 11:39 PM   #23
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And just to hog this thread some more... aside from the Synder mod, it appears a series resistor in line with the thermistor might help with tempcontrol. And then for the really serious, there is this: R & G Electronic Home

I also noticed that the Limp Mode runs the fridge 100% of the time, so we needn't worry about overworking it -- though the gas or electric bill might hurt a bit.
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Old 08-14-2007, 08:28 AM   #24
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Quote:
Originally Posted by grantb4
It's hard to tell which direction the Synder moves the air. It almost looks to me like it pulls air down from the top, but it's hard to tell from the picture. Anyone have any idea? I think the proof would be how does the fridge operate (without compromising it's life).
Pulls cold air from the bottom and pushes it out the top.
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Old 08-14-2007, 12:14 PM   #25
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I think the refer was as cold this morning as before I lost power. I guess from a dead start, in this heat, it just takes a long time on AC to get there. I need to get a thermometer to see what it's actually reading, but I think it's in good shape.

From reading other posts, it looks like the idea may be to run it on gas to cool more quickly and then switch over to AC. That sound correct as a general rule?
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Old 08-14-2007, 12:23 PM   #26
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Quote:
I think I'm going to try one of these:
i just put one in mine last month, works as advertized. nice kit.

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Old 08-14-2007, 04:11 PM   #27
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Dometic's detailed response to my query:

The thermistor should be on the far right fin - towards the top would make it slightly cooler and towards the bottom slightly warmer.

I will do some experiments later this month.
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Old 05-14-2008, 05:40 PM   #28
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Dometic Refrigerator thermistor...

Quote:
Originally Posted by grantb4
Dometic's detailed response to my query:

The thermistor should be on the far right fin - towards the top would make it slightly cooler and towards the bottom slightly warmer.

I will do some experiments later this month.

Our freezer is getting cold but the refer isn't... have fiddled around with the plastic thermistor on the far right fin and it doesn't seem to do anything... The refer has been on since last night (not yet 24 hrs. but close enough). The unit is level.

Anybody have insight on this doo-dad?
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