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Old 04-20-2009, 03:29 PM   #1
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3 year old Dometic doesn't work

Well, I have just about had it with our fridge. It is 3 years old and despite my best efforts – it just doesn't work.
Here's the situation... We replaced out original fridge with a nice new Dometic of suitable fitting. The old fridge would actually heat up on the road, then run fine if it was allowed to sit still.

Now, our new fridge is doing something similar. With us prepping the trailer I start the fridge so it can get all nice and cool – no problems there. It's when we hit the road that the problems start. What happens is that the fridge temp starts to go up and the freezer stays cool. Standard absorption cycle issue, right?
Well, with our old fridge, once you stopped rolling and got all settled out it would work again. Now, the fridge compartment just keeps getting warmer and warmer.

Here is what I do know – the fridge was installed poorly and actually has a few degrees of lean forward (that plus the crunched wheel well and the completely unsealed cooling section allowing dust to come in, it was a very bad job). I have attempted to compensate for level by jacking the trailer in the opposite direction to get the fridge level. It still does not help. I am measuring the levelness of the fridge per Dometic's instructions – using the floor of the freezer compartment if you will.

I have tested the unit per Dometic's instructions and find that it works fine if it is started with the trailer and fridge level enough for comfort. What I have not done yet is to actually pull out the fridge and test it on the ground. The reason I have not done that is because in testing at home with everything still it works. So that makes the frustration level very high!

A little more about the testing I have done based on Dometic's suggestions...
Quote:
After the unit has been operating for approximately one hour, carefully touch the unit at the boiler box and the absorber area. These areas should be approximately the same temperature, regardless of the ambient temperature. Equal heat between the boiler and the absorber indicates the fluid circulation within the unit is good.
which it usually is when all is well.


However, on the road or after towing and settling out the absorber is actually cooler than the boiler – much cooler! And so...
Quote:
One of the faults with a cooling unit is a blockage. This can happen when the unit is operated off-level, or if too much heat has been applied to the boiler area. To the touch, this unit will be extremely hot at the boiler with little warmth at the absorber. In other words, no circulation.


Due to the temporary nature of the malfunction I suspect a temporary blockage due to improper draining in the evaporator section and thus:
Quote:
Liquid trapped in the evaporator sections, caused by out-of-level operation for a period of time. Resetting the refrigerator to a level position will not necessarily correct the problem as liquid can remain trapped even after level is corrected. Shut off the heat source and let the system cool down, then re-start it and observe the temperatures at A and B again after several hours.

Quote:
Blockage symptoms on the newer cooling units almost always, indicate trapped liquid in the evaporator, which can be corrected by proper leveling and allowing the cooling unit to cool off before restarting.
.

O.K. Fine – but I still can not drive down the road with my fridge on because that is when the problems start. We are going to pull the fridge and level it correctly and even put in a fan for improved ventilation. But I believe that there is more to the story. We replaced our axles when we first got the trailer. We had the stock 2800 pound versions and swapped them out for a fresh set of 3500 pound axles thinking that the additional weight would allow us to haul out more things (like beer) if needed.

A very sagacious individual on these forums told me that it might be a bad idea to do that as the trailer will ride rougher on the road. I believe that this may be exacerbating the refrigerator problems we are having. So we will be looking into getting those 3500 pounders out and a set of 2800 pounders in. Hopefully the combination of a better level and a smoother ride will once again allow us to run our fridge as just about everybody else does – running as you are cruising down the road.
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Old 04-20-2009, 05:33 PM   #2
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How out of level is it when "ready for the road?" It seems like it must really be out of level if it isn't draining... I don't think your axles would make that much of a difference (didn't you buy "orginal equipement replacements?"). Even my poorly working orginal axles (bounce and all) allow my fridge to work on the road.....

My beer's on the level of the fridge. BUT... how is the setup for exhausting the "heat" from the coils? Is there some sort of vacume that is being created that does not allow the exhaust to go up and out? However, since you note that the coils are not all the same heat.. then this last theory may be bunk.

Can you post a pic?
Marc
P.S. - what's up with your 54's Cruiser?
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Old 04-20-2009, 05:40 PM   #3
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Here is what I do know the fridge was installed poorly and actually has a few degrees of lean forward (that plus the crunched wheel well and the completely unsealed cooling section allowing dust to come in, it was a very bad job). I have attempted to compensate for level by jacking the trailer in the opposite direction to get the fridge level. It still does not help. I am measuring the levelness of the fridge per Dometic's instructions using the floor of the freezer compartment if you will.

If you are saying the frig is setting in an area that is subject to outside wind currents could it be that the flame is being blown out while you are traveling. This will be hard to test because as soon as you stop the flame would relight. First thing I would do is pull the box and seal any opening that could cause unusual air currents.

I doubt that a slight tilt forward would effect the operation. These frigs are subject to tilt side to side as that effects the return flow of liquid in the unit.
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Old 04-20-2009, 06:41 PM   #4
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Quote:
Originally Posted by 3Ms75Argosy View Post
How out of level is it when "ready for the road?" It seems like it must really be out of level if it isn't draining... I don't think your axles would make that much of a difference (didn't you buy "orginal equipement replacements?"). Even my poorly working orginal axles (bounce and all) allow my fridge to work on the road.....

My beer's on the level of the fridge. BUT... how is the setup for exhausting the "heat" from the coils? Is there some sort of vacume that is being created that does not allow the exhaust to go up and out? However, since you note that the coils are not all the same heat.. then this last theory may be bunk.

Can you post a pic?
Marc
P.S. - what's up with your 54's Cruiser?
Well, almost 3 degrees forward of lean believe it or not. The manual says that the trailer rocking back and forth allows it to drain properly during travel but with that forward tilt I can see that the evaporator coils in the fridge lean down allowing fluid to build up in them. I suspect that it may be enough to unbalance the ammonium & hydrogen mixture or to actually plug up the flow.
I think the back is venting well enough. But the axles and perhaps rougher bumping and less rocking back and forth do not allow it to drain as well.
I am no expert in anything except frustration in this area - we have not had a working in that trailer since we got it. I think the lean must be enough to be causing the problems.

I do not think that the flame is blowing out. I used a datalogger to monitor the temperature over several days about a month ago and I could see the unit cycle on and off at regular periods, except at night when it got cool enough to not need to run. It actually controls quite well. But the flame and cute little "click, click" of the solid state igniter is something we are acutely aware of now and we do not hear that going off and on all the time. I checked it on our last trip this past weekend and the boiler is shielded quite well. If the flame does blow out (which I was able to do by really reaching my head in there and blowing real hard) it just "click, click's" itself lit again real quick.

No, with a hot boiler and cool absorber, I am trusting the lack of circulation issue. I will call Dometic for deeper advice on this....

The '54 is still sitting at the bottom of the driveway but my wife is ready to get working on that. We are going to put a fresh set of rims (not the split kind) and tires and roll it to the top of the driveway to start the overhaul. It will happen.
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Old 04-20-2009, 06:54 PM   #5
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WHAT--- you haven't fixed the reefer yet??

lewster will probably give up the info and then you will keep those gently used axles you promised me. !

spending too much time in the moho I suspect.
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Old 04-20-2009, 07:06 PM   #6
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Maybe the answer is "all of the above". If the fridge is on the streetside of the trailer, the 3 degree lean, coupled with the lean from the crown of the road, bad drafting from the damaged flue area, and possible bouncing from harsher ride of the axles, may be all conspiring to cause your problem.
Then again, it could be internal debris from when the cooling unit was built occasionally clogging things up. We had that problem, and went through 3 cooling units before I gave up and got a whole 'nother new fridge.
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Old 04-20-2009, 07:19 PM   #7
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maybe the guy that put the axles in put one side in downside up. ark ark
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Old 04-20-2009, 07:48 PM   #8
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maybe the guy that put the axles in put one side in downside up. ark ark
Yeah, yeah, I know...you'll be here all week, yuk, yuk...
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Old 04-20-2009, 09:08 PM   #9
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Tim,

You will have your axles! I promise. Kimber and I are already committed to replacing them and after that we will load those suckers in my white box trailer and haul them down in that big 'ol motorhome we have. Only problem will be that we will be bumming wine off you! Lots of it and we will need a place to park. With enough pneumatic tools we might even get them in for you!
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Old 04-20-2009, 09:19 PM   #10
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Proof

Take a look at the attached file. It shows my test that I did after our March trip to Death Valley when the fridge failed altogether. It was not too hot there, normal breezes, etc. But I do know that the trailer was parked on a slope and I did try to level it as best as I could. But I realised later that the trailer was leveled in such a way as to not favor the position of the fridge but rather probably compounded the problem. So that trip found the fridge temps going up day after day.
This test showed that the fridge in fact works fine. The slope off at the end is from a day when the outside temperature was cold enough that the fridge did not need to run.
Attached Files
File Type: pdf Fridge Temp - elec, 3-09.pdf (5.5 KB, 117 views)
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Old 04-21-2009, 08:41 AM   #11
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Your data looks a lot like the results I was having with my frig. Warm summer days and the temperature was up in the 40s.

There are several thinks I have done to atempt to improve the operation. There has been some improvement but still not up to what I want. Airstream does not follow Dometic's instructions when designing the cabinet for the frig. Dometic wants the rear wall 1 in. behind the unit to insure a chimney effect for the air flow over the coils. Instead there is a hugh mass of still heated air surrounding the the back of the frig and allowed to flow around to the sides. This trapped air produces an artifical ambient atmosphere for the frig to have to work in. I removed the frig and made pillow like insulation pockets for the sidewalls of the cabinet and made a sheet metal false wall for the back.

While this did not have as drastic effect has I had hoped for it did improve things. I mention this because of your comment of the crushed wheel well. Is there an additional air circulation in the cabinet becasue of this that may cause the heated air to be pushed alowg the sides of the frig while driveng?
Attached Thumbnails
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Old 04-21-2009, 10:02 AM   #12
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IIRC-- was there not a thread somewhere about how - if the fridge drain line (with the screen) was placed incorrectly that it would let warm air be sucked into the cold box? I can not seem to find it.
Vine View is always open to you B cup, especially if you bring gifts of axles!!!lol
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Old 04-21-2009, 10:39 AM   #13
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IIRC-- was there not a thread somewhere about how - if the fridge drain line (with the screen) was placed incorrectly that it would let warm air be sucked into the cold box? I can not seem to find it.
Vine View is always open to you B cup, especially if you bring gifts of axles!!!lol
A very interesting comment and one easy to test. Put some cotton in the end of the hose. This will stop any flow of air but will pass water.
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Old 04-21-2009, 01:34 PM   #14
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Lightbulb Reffer Madness

Well Tim, you seem to have all the bases covered, done your homework, got the technical readouts and logged the numbers. I'd like to propose a different type of logging!

As a full timer, these temps of high 30's and low 40's with fans and baffles are just unacceptable.

My new fridge started acting up 3 years after I installed it. That was 3 years ago.

I put a remote temp meter in, and watched the temps start to rise regardless of setting or the fans I placed in and outside the unit.

On the road and desperate, headed to Burning Man 06, I pulled into a Camping world. Parked next to a class A, the couple just had a new fridge installed 2 days ago.

Ya know what, their temps were running about the same as mine, they were not leaving till they got satisfaction.

They were told that considering the outside temp that low 40's high 30's were the best they could hope for. Well they were not buying it.

I don't buy it either.

An old timer told me once to tap the coils if ever the fridge acted up. Well parked there at Camping World, I decided to beat the livin &$%@ out of the coils with a quarter round log I had in the truck.

Immediately the temp started to drop. With the #2 setting, the temp settled in at 34-36, with an outside temp of 88.

I stayed 24 hours and the Class A folks wanted to trade their NEW unit for MY old unit, LOL.

The unit worked flawlessly for 18 months, after which time I administered another beating, with grand results.

4 months ago, in ambient temps of around 78-82 the same thing started. Beating did not seem to work, so I ordered replacement coils. In the interim, I continued the beatings, adjusting style, duration, cadence, and materials of course.

Before the new coils could arrive, the fridge temps returned to normal. That was 4 months ago.

As I sit here, after traveling 800 miles and overnighting in uneven parking lots, the box temp is 33.3, ambient temp 79.6.


There is something to be said for having a large tow vehicle, for I am now carrying around a spare set of coils.

Will the fridge ultimately fail, of course, they all ultimately fail. I've gotten an additional 3 trouble free years from my unit, for a total of 6 which still stinks IMHO. I may get more?

Specs and technical bulletins be dammed, sometimes only a good quarter round pecan wood log will do

Luke, I mean Tim, use the force

Michael
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