freezer works - fresh food doesn't!

[BOBHASTINGS]

Hi gang,

I've got a '78 Tradewind with the original Dometic RM100 2 door refrigerator. PO said it would work on AC only. Tried fridge on shorepower AC this week on our first expedition to FL state parks. Seemed to work OK, freezer made ice pretty quickly and fresh food compartment seemed cold. Didn't pay a lot of attention to the fridge once we saw the ice made in the freezer.

Moved to the 2nd FL campground the next day. Plugged into shorepower and freezer got cold and made ice in a couple of hours, same as the 1st time. However, this time, fresh food compartment never got cold. Fins on inside back wall of FF compartment never got cold!!!

Checked at outside door and heating element was hot (used the infallible HTT (hand touch test - ouch! ) Searched thru the forum but did not find this kind of problem.

Worked for GE Major Appliance for 20 years so have a fair understanding of refrigeration cycles. Actually bought and dismantled a couple of old ammonia absorption cycle fridges just to see how they were built. But this one stumps me. I find it hard to believe that a little ammonia leaked out between campgrounds to cause only the FF to stop working but not the freezer also! I even adjusted fridge level to within a gnat's ass to eliminate the possibility that the unit was out of level enough to cause a problem.

I have not tried to light propane yet. Figured to fix 1 problem at a time.

Fridge gurus - unite!! Any ideas???

I'm heading home to Cinn. so will sign back on tonight.

[Chas]

Bob,

The lower fridge section is cooled by a secondary effect off of the freezer. The fins in the back of the fridge section are in direct contact with the piping that directs the cooled ammonia solution from the freezer compartment back into a reservoir at the bottom of the fridge where the process starts over again. There could be a problem with the special mastic that they use to transfer the cold onto the finned plate in your fridge. It would be safe to say that the sealed ammonia system and the heater element which produces the reaction are OK. It takes a day or so for the lower fridge portion to get sufficiently cold, maybe even longer in the hotter days of summer.

For more info check out this link,

http://www.gasrefrigeration.net/how_they_work.htm

(On edit, I'd say there is probably nothing wrong with your fridge. If you were to get the gas portion operating I am sure you would see a big difference in the cooling. I have usually started all of mine on gas and then switched over to 120 volt operation after a day or so)



Chas

[87MH]

....that there is too much heat building up in the "systems backside area, or (conversly), not enough ventilation to remove the heat from the heat/generator/adsorption process.

Search threads for ""Fridge not working".....

Several ideas for increasing heat transfer efficiency have been provided.

You can run a simple test by placing a small 110 fan in the outside 'fridge access area (point it "up"), and observe if the increased air flow helps your problem.

[87MH]

......have you checked your lower door seals for condition and good contact?

It doesn't take much of an air gap to prevent the 'fridge section from cooling properly.....does the light turn off?

Check the lower gap for broken or missing rubber seal, or a sprung door that would require a mirror for lower (floor) inspection.

[pjlingl]

Bob:
I had the same thing happen to my 93 Excella while I was in Fla. in January. I tried everything including wiring the 120 directly to the heater. I finally found out that the ammonia solution crystallizes ( especially the cromate product added to it to retard corrision) and blocks the return ducts enought to reduce the cooling in the food section to "zip". The freezer worked great - was operating at or near zero F. The fresh food compartment was operating at about 60 degrees. I finally gave up and replaced the fridg - about $1300.00. I under stand you can get your old unit rebuilt for about $400-450. I have also heard, on the older units, one can remove them and turn them upside down and let them sit a few hours and then upright and reinstall them and it cures this condidtion at least for a while. Some people claim this procedure cures them for a long duration. Good luck. Jeff

[Navigator]

Same problem here. Shut refrigerator off for a day with doors open. Then back off on the thermostat to 1/2 of your original setting, then restart. Worked for me.
Dick

[BOBHASTINGS]

Thanks for all the 'tricks' for attacking my fresh food compartment temp problem! I will try them all in order of difficulty!!! I think bouncing the fridge on it's head will be LAST!

Will report back as soon as she comes back from Paul Sherry RV - 2nd visit for furnace problem. First visit was safety check and replacement of the motor. At that time, they said A-OK but 2 days into our 1st camping trip to FL, the heat stopped coming! Fan motor kept blowing but would not get hot. Hope it's something simple - we debated replacing the whole furnace at the time we knew the motor was bad but PSRV said should be OK with just the motor.

We'll see!!!

[TomW]

In the furnace section of my owner's manual under troubleshooting, they discuss the possibility of the LP bottles' regulator possibly contributing to furnace problems. If your furnace is like mine, i.e. no printed circuit boards, and YOU light the pilot light, the following may pertain to you:

As I recall, the manual indicated the regulator isn't real thrilled regulating just enough gas to run a pilot light, and pressure surges may result. If the regulator is suspect, it can be absolved by running another gas appliance while the furnace goes through a cycle or two.

Like I said, this may not apply to you, but I thought it was a cool thing to pass on.

Tom

[ipso_facto]

I have the same issue... the fresh food section does not cool below 60F, while the freezer is very cold.

The fridge was replaced in '95, so it's not that old.

The camper is currently not level at all, could that be the reason, even on electric? I recall it worked well just a few weeks ago, when it was level, though I fail to see how being level can affect its functionality on electric.

[87MH]

Originally Posted by ipso_facto

The camper is currently not level at all, could that be the reason, even on electric? ........ I fail to see how being level can affect its functionality on electric.

The "electric side" is simply a heater element, not a compressor. When running on electric the electric resistance element is used to heat (boil) the ammonia instead of utilizing a gas burner to do the same thing. Other than the heat source, the boiling/adsorption/cooling process utilizes exactly the same components.

The rich/lean ammonia separation/condensing unit requires a gravity slope to function properly, hence the requirement for a reasonably level unit.

On mine (almost 20 years old), I have found that if I start it at least 24 hours prior to a trip (after it has been sitting unused for a couple of weeks or more), it seems to function better.

I very seldom need to run the unit on gas. Given the increased performance of the newer compressor type units (efficiency, insulation) and the almost universal availability of ice for keeping things cool on short trips (making it into an "ice box" that at least some of our grandparents used), I don’t know, should the current unit head south, whether or not I’d replace the fridge with an RV/gas/electric model, or just go with an apartment type conventional refrigerator as a replacement.

[ipso_facto]

Thanks for the feedback, I will level and report progress. It should work.

[Sav'h Steve]

I had always looked at the front to back leveling and got the left to right done with the wheels....

But after reading these posts (and having problems getting cold enough) I went out to the working refrig and checked level.

Sure 'nuf the fore to aft was pretty close by using the power jack. And left to right was fine for the trailer, but the FREEZER PLATE was bent down in front!! It looked to be 'bout 1/2 inch lower towards the door from the back of the freezer plate.

Now with a '90's unit, should I BEND the freezer plate back up to be level with the TT unit??

I understand that the pre '80's units were more suseptable to being slightly unlevel. Also they responded better to the 'burping' procedures mentioned earlier.

Anyone try to bend their freezer plates?

Steve in Savannah

[thenewkid64]

Originally Posted by 87MH

---should the current unit head south, whether or not I’d replace the fridge with an RV/gas/electric model, or just go with an apartment type conventional refrigerator as a replacement.

Dennis,

If or when the current one dies:

Since you have a MH with a big battery drawer, look at the AC/DC Norcold units. They utilize a compressor but are designed to run the compressor off DC if no AC is available. It will be noisier than what you have now, but will stand up to the rigors of travel better than a home style unit.

[Inland RV Center, In]

The warmer the ambient temperature, the more critical the levelness of the freezer compartment becomes. It must be level in all directions, when not in motion.

For those that have experienced a freezing freezer but the lower section is 50 to 60 degrees or more, not all is lost.

Shut the reefer down, and leave it alone for a couple of days. If possible, tow the trailer for a couple of miles, so that the ammonia/water solution in the coils can move around.

Relevel the reefer freezer plate, and fire the burner up again.

If your lucky, or successful, the reefer will now cool correctly.

If it's performance is still poor in the bottom, you now must make a choice.
You can replace the cooling unit, or, replace the reefer.

Keep in mind, that if the refrigerator is functioning correctly on electric, then the problem would not be the cooling unit, but would be somewhere in the gas portion.

Andy