More Dometic Refrigerator Questions

[bobnelms]

Hi all,

Our freezer temps are usually 15 deg F, but even with nothing in the refrigerator I can't get the temps lower than 45 F.

I'd like to check the resistance of the thermistor, but I don't know which wire is the thermistor. I've attached a photo in hope that someone can ID the correct wire.

I also took off the upper vent from the outside of the RV, and noticed a piece of plywood that covers a lot of the opening. Is this piece of plywood supposed to be there??

Thanks ahead of time.

[chuckster57]

That piece of wood is supposed to be there.

Since your fridge is on a slide, You should have some fans that run when the upper cooling unit reaches a certain temp, are you hearing them? At the right end ( in first pic) is the thermalswotch. jumper it to make sure the fans work, then if they do, see if the fans come on with the refer turned on. I think the set temp for that switch is like 120 degrees, You can use a heat gun to see if you can get the switch to operate. If it doesn't then I would start with that.

The thermistor plugs into the control board that is behind that cover. Should be marked. If not then its the two conductor, WHITE insulation wire. You can unplug it and then start the fridge and it will force the cooling unit into MAX COOL mode to rule it out.

[bobnelms]

Chuckster57, this is great information. A followup question... you say that the thermistor plugs into the control board that is behind that panel -- do you mean behind the wooden panel in photo#1? If so, how to I get out that panel? It seems it extends a long way down into the rear of the refrig. Is it glued? Thanks so much..

[chuckster57]

Im sorry, the control board is behind that black cover in the second picture. You should have two tabs on each side that you use a small flathead screwdriver to pop loose. The screw on the top holds the control board in place.

[retiredusps69]

I would remove that wood panel first even if you only cut the part out the size of opening.The thermo switch also called a snap switch should be hooked up to the hot lead on the second picture.Usually red and possibly have a 2 amp fuse in the line.You really need to remove the wood there is not enough air flow.I have our fridge set on the controler in side set midway and it is reading 35 lower and - 6 in freezer.I have 1 fan in fridge and 3 behind vents.1 lower 2 upper.Also pack some kind of insulation above the fridge and down the sides from the rear to remove dead spaces. If snap switch is bad you can get them on ebay 5 for like $8.00. Just search snap switches. Or just jump wires until you get a new one.

[chuckster57]

DO NOT remove any of that wood! It is critical for proper air flow.

[retiredusps69]

Chuckster I hate to disagree he said that it was in a slide.The vent is more than half way blocked off. If it was not in a slide and had a roof vent maybe so.He can do as he pleases but he has no amount of open vent.Heat rises and does not like to turn corners unless forced with a fan.That is almost a 90 degree turn. I doubt anyone has seen a vent blocked off that amount.He has nothing to lose if it does not improve!!!!!!

[chuckster57]

Chuckster I hate to disagree he said that it was in a slide.The vent is more than half way blocked off. If it was not in a slide and had a roof vent maybe so.He can do as he pleases but he has no amount of open vent.Heat rises and does not like to turn corners unless forced with a fan.That is almost a 90 degree turn. I doubt anyone has seen a vent blocked off that amount.He has nothing to lose if it does not improve!!!!!!



Every fridge I have seen in a slide will have that board and fans located below the upper set of fins to help with air flow. Look at my signature, and you’ll find I’ve seen plenty of refers in slides and I might know what I am talking about. If you can locate installation guides from Dometic and Norcold, you will find that it is required and I have even ADDED more to some units.

[Brentw]

Yes, i suspect without the wood divertor, you would lose your airflow before it had a chance to flow thru the finned portion.

[retiredusps69]

Yes the baffle is from the outside wall to the edge of the coil forcing the air thru the upper coils. NOT BLOCKING THE VENT.Check out any after market site for baffles and fans. Also check the manufacters site for the install manual the baffle does not block the vents.

[ctbruce]

Yes the baffle is from the outside wall to the edge of the coil forcing the air thru the upper coils. NOT BLOCKING THE VENT.Check out any after market site for baffles and fans. Also check the manufacters site for the install manual the baffle does not block the vents.It's not blocking the vent. There is a large opening at the back of the picture. It is put together as it is designed. If you take the time to look at the manuals you will all is correct.

Not sure how many RV fridges you've fixed in your lifetime, but as far ad knowing what they are talking about and having real world experience in working on these, my money is on Chuck and his suggestions to fix them.

If your fix was followed and it didnt work, what would be your next fix? Put the baffles back? SMH.

[bobbecky]

This is from the Norcold install manual for our 1210 fridge. The red arrow points to the baffle installed in a slide installation .

[bobbecky]

And this is a photo from the same manual for the Norcold that shows the baffle installed in an enclosure that isn't as deep as the previous photo. The baffle is item #26 in the photo.

[bobnelms]

Chuckster57, first of all I will NOT remove the wooden baffle. I never like to tamper with original design unless I thoroughly understand what I'm doing. As you and others have said, that wooden baffle is obviously present to assure flow past those upper fins.

Another question: inside the refrig, the thermistor is placed in a "clamp" that can be positioned up or down on the fins inside the refrig. If it's place high, it's supposed to get colder. If it's placed low, it's supposed to get warmer.

WHY? Is it because hot air rises, and so it ought to be hotter at the top of the refrig?

Another question: Is it the fins themselves that cool-off the inside of the refrig? If so, how do the fins get cold? Can you provide a schematic of a typical dometic refrig?

Thanks so much.

[gluck]

I was questioning our fridge as well, I have attached an image of our install which shows the plywood as yours does, however ours has a piece of metal that is curved over top as well. Not sure if it supposed to be there or not because I don't see one on your top vent.

[LHaven]

inside the refrig, the thermistor is placed in a "clamp" that can be positioned up or down on the fins inside the refrig. If it's place high, it's supposed to get colder. If it's placed low, it's supposed to get warmer.

WHY? Is it because hot air rises, and so it ought to be hotter at the top of the refrig?

Yes. The higher the sensor is, the more active cooling the fridge has to exert to keep it happy.

[Steveo57]

Chuckster57, first of all I will NOT remove the wooden baffle. I never like to tamper with original design unless I thoroughly understand what I'm doing. As you and others have said, that wooden baffle is obviously present to assure flow past those upper fins.

Another question: inside the refrig, the thermistor is placed in a "clamp" that can be positioned up or down on the fins inside the refrig. If it's place high, it's supposed to get colder. If it's placed low, it's supposed to get warmer.

WHY? Is it because hot air rises, and so it ought to be hotter at the top of the refrig?

Another question: Is it the fins themselves that cool-off the inside of the refrig? If so, how do the fins get cold? Can you provide a schematic of a typical dometic refrig?

Thanks so much.

All good questions. Funny thing is the manual for my fridge doesn't even mention the thermister. It says it has a fixed setpoint. The thermister is not physically attached to the cooling plates it's just suspended loosely in the dead air space between the fin and the wall. I've read that it only gives you a few degrees +- of the fixed setpoint.

The cooling fin assembly is just fins attached to a plate which is then attached to the cooling unit. You'll notice the freezer doesn't have fins but if you feel the back wall it's cold. The fridge side works the same way but it had fins on a plate attached to the back of the fridge.

[fjr vfr]

Funny how I stumbled on this thread. I was just going to start a search. :)

We are a couple days into a 10 day trip and my fridge isn't as cold as usual. It's working but cools like on a low setting. Some things in the freezer are on the soft side and the lower section isn't as cold as usual.
I checked to make sure the thermistor in the fridge is in the upper position, and it is. I ran it on gas and 120...same results.

I'm thinking the thermistor... so my next step in the morning will be to unplug the thermistor and see if it gets cold.
Hope that's the problem. Like they say, it's always something.

[PSD Andy]

I was questioning our fridge as well, I have attached an image of our install which shows the plywood as yours does, however ours has a piece of metal that is curved over top as well. Not sure if it supposed to be there or not because I don't see one on your top vent.

Our Dometic fridge has the same black aluminum panel. Our fridge is in a slideout. Seems like a proper install. The factory had a fan below it so when it gets real hot ambient temp the black panel has the fan air deflected/moving over the fins on the tube. I went a year and half with that setup. This year I added the two fans at the top to push more hot air out of the top vent and that's improved the interior fridge/freezer to get colder when the sun is cooking on the camper all day.

[chuckster57]

The basic premise as I understand it is this:

Cooling solution is “boiled” by either a heating element or a flame. As it travels down the coils, it “absorbs” heat from the interior by use of plates and fins. I think as it moves to the lower portion (fridge) it’s ability to absorb heat is diminished and that’s the reason for the fins- more surface area. There is a thermal mastic that is applied to the tubes of the cooling unit before it’s attached to the “cabinet” to help conduct heat.

Any number of reasons can cause issues with temps: poor air flow, blocked cooling unit passages, loss of cooling solution, bad door seals, etc. there are forms issued by refer maker that we fill out to help them determine why it isn’t cooling correctly. Most often when a fridge is in a slide and the freezer is okay and the fridge section is too warm, it’s either the fans or the door seal.

This is based solely on my experiences, it’s not the ONLY reason, but seems to be the most common.

[fjr vfr]

What are typical temps for the fridge and freezer? Is 23 deg in the freezer and 37 in the fridge normal?

[JRTJH]

In moderate temperatures, mine runs about 15-20 and 33-36. When we were in Las Vegas earlier this summer, it ran 20-30 and 38-40, depending on where the sun was hitting the trailer. When the refrigerator vents were in the sunshine, temps rose slightly, when in the shade, they fell, but with 100+ air temps, the refrigerator worked harder and had trouble "keeping up" with the temps we see when the air temp is in the 60's or 70's.

So, depending on the circumstances that you're in, what you have can be normal. There are some things you can do to improve the cooling. Shade the trailer sidewall where the refrigerator sits, make sure the fans are clean and properly adjusted (and running when it's hot) and refrain from "grazing" with the refrigerator door open. Many people will open the door, search for what they want, stand and contemplate their decisions and "dilly/dally" with the door open. Doing that allows much of the "hard to obtain cold air" to escape to the floor (if you stand there barefoot, you know what I'm talking about).

Ideally, open the refrigerator only when necessary, know what you're getting and do it quickly with the intention of closing the refrigerator door as quickly as you can. Once the cold air is lost, it takes significant work for the refrigerator to recover. Conserving the cold will help keep the temps at their lowest possible point.

[fjr vfr]

Thanks JRTJH.
It's possible I'm trouble shooting a problem I don't really have? We are at the Outer Banks, NC and the last few days have been in the 90's with high humidity. So maybe I'm expecting too much from it?

I must also admit to sometimes "grazing" as you put it. :lol:
I have a couple extra fans installed in the back and have been running them, but the weather's been very uncomfortable outside.


I did unplug my thermister and it ohm'd out at 743k ohms. I left it unplugged for now. I have 5 temp settings on the eyebrow panel. I guess they do nothing if the thermister is unplugged? Is that correct?

I think this board may have been replaced at one time. It shows a date 10215 on the back, (that's how it's written.) I assume that's 2015 something. The trailer is 2011. :confused:



Thanks for the help. I'm on another learning curve. :)

[nellie1289]

i have a temp control on the back of the upper fins in my refridge. it is a little plastic thing that slides up and down that appears to do nothing. what is this for? i have no temp issues in my fridge and mine is in the slide by the way, it does take a while to cool down though, always start it up 2 days before our trip.

[chuckster57]

i have a temp control on the back of the upper fins in my refridge. it is a little plastic thing that slides up and down that appears to do nothing. what is this for? i have no temp issues in my fridge and mine is in the slide by the way, it does take a while to cool down though, always start it up 2 days before our trip.



The white “bulb” is the thermister. It’s held in place by that plastic slider, and moving it up will change the interior temp of the fridge. You may not notice 2-4 degrees unless you drink a water or milk taken from the fridge.

[nellie1289]

not in my trailer right now but is up to cool it lower or down to cool it lower, half the time i just see it hanging off the metal, it seems so weird to me.

on edit, just saw this on you tube, amazing

https://www.youtube.com/watch?v=Gsihtpi_kqc

[Rinsrig]

He isn't joking, DO NOT REMOVE THE WOOD!!! As an RV tech, I can tell you that that piece of wood is exactly where it needs to be and it is exactly the size it needs to be. Do NOT change anything about it.
In photo 2, you have the photo of the black box, down in the corner of the fridge. There is a white wire leading into the black box (not the one with the red and black wires). The white wire leads into the box and is usually a blue and brown wire, that is your thermistor wire. Seeing as how you have the baffle in there, there should be at least one, if not 2 small fans that force the air up, and out across the fins on the top of the fridge (hence the plywood baffle) and out the top vent.
call Dometic and order a new thermistor, they are not expensive, they are a bit of a pain the butt to replace, but it can make all the difference for proper cooling. Also, make sure that the fans are working correctly. There is a sensor at the top of the fins, usually on the right side that controls the fans, make sure that it is working correctly, you can use something to heat it up (don't melt it) to see if your fans engage, if not then replace it, also make sure you have power leading to your fans (12 volt)

[Rinsrig]

Thanks JRTJH.
It's possible I'm trouble shooting a problem I don't really have? We are at the Outer Banks, NC and the last few days have been in the 90's with high humidity. So maybe I'm expecting too much from it?

I must also admit to sometimes "grazing" as you put it. :lol:
I have a couple extra fans installed in the back and have been running them, but the weather's been very uncomfortable outside.


I did unplug my thermister and it ohm'd out at 743k ohms. I left it unplugged for now. I have 5 temp settings on the eyebrow panel. I guess they do nothing if the thermister is unplugged? Is that correct?

I think this board may have been replaced at one time. It shows a date 10215 on the back, (that's how it's written.) I assume that's 2015 something. The trailer is 2011. :confused:



Thanks for the help. I'm on another learning curve. :)
Plug the thermistor back in, you are showing correct ohms on it, it means it is working correctly. Your fridge will not work correctly without it plugged in. The date code is Jan 02, 2015. If your fridge is not cooling sufficiently, slide the thermistor (inside) up the fins to make it cooler.

[Ridemytractor]

The reason for the plywood is to force the fan air through the coil that’s how mine is fixed 35 in the refrigerator and six in the freezer

[pitman44]

FWIW, I'm not an RV refrigerator expert however I do own a residential HVAC business. In modern HVAC equipment there are TONS of thermistors. Well, maybe not tons, but a whole lot of them are used. I can tell you with all but 100% certainty thermistors don't drift. They either work correctly or not at all. If they're not open or a dead short, the thermistor isn't the problem.

As far as RV refrigeration, here's the best site I've found with lots of DIY videos. Ours is in a slide as well and wasn't keeping as cold as I wanted it to. Here is the link to their video on potential issues with refrigerators in slides. I hope you find this helpful. BTW, my problem was an ID10T error as my daughter says.

https://www.youtube.com/watch?v=T021bascFiY

[Bignewsantafe]

Does anybody know what this part is for? It came with our 2016 Alpine frig.
Thanks.

[LHaven]

Do you have two of them?

Whenever I see a pair of identical leftover dinguses in a refrigerator kit, I try to see if they are designed to keep the doors secured but in an open position, i.e., for storage. The one I have currently for my Dometic looks like a credit card with slots in it. You didn't say what brand your refrigerator was.

[chuckster57]

Does anybody know what this part is for? It came with our 2016 Alpine frig.

Thanks.



That is for keeping the doors ajar when it’s not in use. The fridge and freezer doors “hook onto” the center piece for normal operation. When storing, that piece slips over the center post and the doors hook onto it leaving a gap for air circulation.

[Bignewsantafe]

That is for keeping the doors ajar when it’s not in use. The fridge and freezer doors “hook onto” the center piece for normal operation. When storing, that piece slips over the center post and the doors hook onto it leaving a gap for air circulation.

Spot on Chuckster! The doors never did like to stay a little open when I would try to leave a gap for air flow when shut down.
Thank you.
:cool: