Charging old Dometic Reefer

[smily]

My Dometic gas / elec frig gets cold but not as cold as it could be.

Any one ever "charged" an Anhydrous Ammonia refrigerator before?

Also thinking of recharging my AC.

I have a 27' 1971 Overlander AS.

Any suggections where I can get advice is greatly appreciated

Ken

[thenewkid64]

How cold is cold?

Please let a professional do the refer if you can find one close to you. The ammonia in the refer can be very flammible and is not so good to inhale either.

Here is a link to a company that handles repairs and recharges.

http://www.gasrefrigeration.net/

You may just want to be sure that your heat sources are working properly, the flue is clean, etc. Itwill not run like the one in your house. It takes longer to cool and will not get quite as cold.

As to the AC, does it cool, what type is it?

[smily]

The reefer actually will freeze up in the freezer compartment but the refrigerator compartment does not seem to get very cold.
Of course my wife has concerns.

I notice that the door indcates that it is automatic defrosting.

If this is the case, why does the freezer "ice up"?

There is a "drip box" under the element that appears to be placed for defrosting but I never see any water in it.


I have ran the unit on electricity when we first bought it and it seemed to work a little but it seems that it works much better on gas.

Since the first running on AC and denergizing, It has not worked on AC since. Any ideas as to why it does not work on AC?
I have verified that there is AC at the outlet that the Reefer is plugged into. I supect that there is a problem internally. but I have not delved into it. I am very savvy to AC and working on electriccal components.

Thanks for the reply,
Ken

[thenewkid64]

If your refer is original you need to be prepared for the worst. The symptoms you describe could be a cooling unit failure. To check this I would reccomend leaving the unit with the freezer door closed for a few days, with the refer off. When you open it see if you have an ammonia smell. I just went through this 2 months ago and ended up replacing the refer. The freezer would freeze, and then thaw, and then freeze. All the while the referigerator portion would not get below 50 degrees. Cooling units can be replaced, but you need to have a tech that not only knows how to do it, but is willing to do it. Most shops just want to install a new refer.

The autodefrost is a function of small heat strips running under the metal that makes up the door frame. This feature is really to stop the condesenation on the frame from happening. The freezer plate will frost up if you have a high humidity level in the coach, as well as it could be a sign of the need for new gaskets.

The drip plate in the fridge portion is to colect the condensation that will occur from opening the door and the air getting cooled. the units will only drip if you have acheived the proper temp/humidity levels to condense. You may have a little plastic tub on the back of the unit to collect this moisture,. This is a item to check if you are dripping as if it is cracked/missing you could drip the water on the floor and start a larger problem.

As to the refer not running on electric, is yours a manual model or does it have a circuit board? The circuit boards have a nasty habit of going out and making the whole unit act strange. Hmmm...............

[smily]

Thanks for your prompt reply,

I do not see a circuit board any where. Where would it be if I had one?

I think my unit is manual but I am certainly no authority although I am technically savvy with most electrical and electronic devices.

I have not removed the cover plate to what I assume is the heater element.

I have had the door shut for many days at a time while in the off mode. When I opened I did not notice ammonia odor but I was not checking for it either.

I will check this this evening seeing that it is in the off mode now and has been for at least a week.

Thanks,
Ken

[thenewkid64]

Ken,

If there is a knob in the reffer that you use to switch from gas to electric, and another to set your temps, you have a manual refer.

Manual is simpler to fix and diagnose when something goes wrong.

Normally a fridge with an electronic control system has exterior controls and indicators to tell you it is on.

Since you seem to have a problem on electric, you may want to check the thermostat. I would reccomend leveling the rig all 4 ways and then firing up the fridge. Not leveling the unit is the fastest way to ruin an ammonia fridge. Put a half full of water milk jug in the freezer and load a few 12 packs of something in the fridge. The units always work better with stuff in them. Also place a thermometer that you know is accurate in the refer and let it run for 48 hrs. If you can get the fridge to 40-44 degrees, save your $ for some other project. If not then you need to look further into the controls of the fridge as well as the cooling unit. A slow leak may not be noticable to the nose. I had a catastrophic system failure so mine was strong.

[74Argosy24MH]

Also check the electric heating element. They die with age. If it is manual the only things really there are the switch on the gas/electric switch, the thermostat and the heater.

Home refrigerators have small fans which move the air internally. One of the best things I ever bought was a little fan that runs on 2 D cells and helps circulate the air in the RV refrigerator; I have seen them at nearly every RV place. It runs 24/7 for a month on a set of batteries, make a lot of difference.

John

[davidz71]

Smily,
I ran a test on my RM100 Dometic frig. on electric. I started with the thing 1/2 full of canned and bottled beverages at 5:50 p.m. with an inside temp of 84 degrees. At 10:45 p.m. the temp was 60.3 degrees. I went to bed and at 6:30 a.m. the next morning the temp was 36.5 degrees. I used a wireless temp moniter so that I did not have to open the frig. door except once when I lost the signal from the remote moniter inside to my base station temp gauge. I didn't measure the freezer temp but I imagine it was well below freezing. This was set on 4 by the way.

Once you start going into the frig. every once in a while and the outside temps are in the 90's, frig. temps stay around 42-46 degrees in mine. If you check the Interior Resteration, Appliances-Refrigerator forum a couple months back, you will see my list of times every 15 minutes or so and the corresponding temperatures registered.

[davidz71]

There is also a solar powered external fan available through Camping World that helps keep the temps down in the outside frig. compartment. I can see where this would help especially if your main door opens back over the outside compartment door and blocks part of the airflow like it does on my trailer.

[featherbedder]

last year my rm760 could not turn to elect. Started manually on gas now does not work either source, can not smell ammonia. Prefer not to change reefers as my76 is still original as pur. new. plus lots of cabinet removal to remove reefer.