Refrigerator - thermostat or recharge?

[Robert Allred]

Original Dometic fridge in my '78 has had some problems last summer, and again this one.  First on gas operation, it would freeze the vegatables over night, seemingly regardless of thermostat setting.  Now, just the opposite, doesn't seem to cool at all.  I've found a replacement thermostat, $76.00!  While I'm at it, is there a way to verify that the ammonia absorbsion cycle, i.e. the sealed portion of the cooling unit, is operable?  Can it be serviced/recharged, etc?
Thanks,    
Robert
mailto:robertallred@aros.net">robertallred@aros.net
AllredsMotorsport.com

[Richard Peterson]

Robert, the first thing to check to is to see if the pilot is lit in the heating area of the unit.  You find this in back, behind a little door which allows you to access the burner.  If you have heat, the unit should work if the  ammonia system is intact.  You can also check it for 12 volt operation and 110 volt operation the same way by feeling the area around the heating units. These are in the same area as the gas burner.  If you have heat, and no cooling, then the ammonia system or thermostat is failing.  If you have cooling on any one of the systems, then the ammonia system is working and you problems are elsewhere.  When did you last use the unit?  Sometimes if a system has been idle for a long period, it can be revived by removing it from the coach and turning it over to every side so the liquid has a chance to "slosh" around in its system.  Blowing out your gas feed from the valve to the burner may also be a solution.  Let me know.  

[Robert Allred]

Thanks, Richard.  
The unit was last used about a month ago, and three or four times before that     this season, beginning in March.  I have confirmed that the burner functions properly, as I actually light the burner by hand from outside the coach.  There is a bit of cooling effect, after letting it run (burn) for two days, the inside of the freezer section is cold to the touch, but not enough to freeze ice, nor, drop the main are below 70 degrees or so.  Its hot outside, high 90's during afternoon here in Salt Lake, which may be part of the problem, but the fridge used to cool better even on such hot days.
I've checked the coach roof air vent, and the space behind the fridge for ventilation, and I've run it the past two days with the coach fridge access door open, to try to ease ventilation up and over the coils on the back of the unit.  No blockage to air flow found, and no help to cooling performance.  This problem seems to have been coming on gradually.  Leads me to think it is either a bad thermostat, or perhaps blocked ammonia circulation or not enough ammonia.  Hence my question, can the sealed system be leak checked, recharged?
I hadn't heard about the removal, turning fridge over, etc, to "slosh" the liquid around.  Would this remove/disolve the fabled "crystals" that are said to form if unit operated when not level?
Model # is RM66E, serial # 74 0088, if that indiates a made in '74 model, its given good service for a long time.  Since new ones are nearly $900 I hope it can be serviced to the point of delivering better cooling for a few more years.  Thanks again for your thoughts.  

[Richard Peterson]

From your activities so far, I'd guess you do have an ammonia problem.  I don't know the answer to the crystal question, but my experience in turning the unit over was a good one.  My unit works great.  Only problem I've had was a burned out 110 volt heater which is easy to replace.  I found a place on the net which re-builds units like ours but I can't remember who they are.  Seems to me they are located in Washington State somewhere.  You might look for them as they had lots of information on operation and theory of ammonia cooling systems.    

[FREE BIRD]

I had same problem. I found out thai it is important to be on a level surfice for it work good. I tried it in my driveway which is at a 10% grade and it never got cold. When I  moved the rig into the street it then got vary cold.

[Robert Allred]

Here's an update on the poor performance of gas/electric refridgerator.  Local parts and service company, with long time experience servicing RV appliances advises that rolling cooling unit over is a temporary fix at best, and not likely to provide more than a few days
improvement, to poor performance caused by crystalization or leakage of the ammonia solution in the cooling unit.
Replacement cooling units are still available, about $400, as are some new gas thermostats.  Some other parts for '77 vintage units are no longer available!  So, I'm faced with the decision to repair this one by replacing the
cooling unit, or buying  a complete new refridgerator, $850 plus installation, involving some modifications to my Clipper's cabinetry, as there is no exact fit replacement available.  Probably total around $1,200 for new.  Coach only worth $5,000 probably, so I think I'll go repair, and hope it will last for the remaining life of the coach!

[Conrad]

I replaced mine a few years ago.  Camping world during a sale.  I have no more than $900 into it.  If you are handy with a table saw and some hand tools it shouldn't be a problem.  I had to take my door frame off to get the new one in.  It is a little bigger than the old one by about 1.5" Width.  Just wide  enough to offer me an opportunity to reseal my door    I made sure the batteries were all disconnected, labled the wires, made sure the propane was off    .

[Plante]

I replaced mine a few months ago.  The old one just sqeezed out the coach door but I brought the new one in through the passenger cab door - after removing the seat and engine cover.  The width was the same as the old one but I moved the shelf above it up a couple inches and because it is deeper I bought some moulding(about 1 x 2), screwed the moulding into the existing frame and the new fridge into the moulding.  It looks fine and works great.  I had to buy a short length of flex gas hose with adapters to hook up the propane and ran the wiring for the automatic lighter through the furnace compartment under the fridge.  It wasn't nearly as tough as I thought it would be.  My unit is a '78 rear bath party model.  I have about $900 invested also.