Fridge just took a dump...

[Taranwanderer]

Originally Posted by Still Kickin

Taran, I'm not sure you read my suggestion correctly as you talk about "Ford AC". I am trying to point you in the direction of Ford's refrigerator service troubleshooting information on the net, for your Dometic fridge issue, so I will suggest one more time. Just sayin'

I got it, I've been watching their videos, very helpful and informative. Thanks! And the rig is level.

Now for today's mystery: after it cooled down on gas last evening, I turned the switch over to "Auto" and let it run on electric, figuring that when I went out there this AM, it would be defrosted and warm again and that the electric heating element would be the culprit. NOT SO FAST, JUNIOR. Went out this AM, and it's still cold--like totally working normally. If it's set to Auto, I'm assuming its running on electric only. Is it possible that it just needed to thaw out and then resume working normally? Is it possible that turning off both the 120V AC and the 12V DC supply caused the board to "reset" somehow? I'm really at a loss. The analytical in me is thoroughly vexed--how could it just randomly defrost itself, and then be working fine after cutting power? My next test is to turn it off again, let it warm up to room temp (thaw) and then see if it will cool down on electric only.

This is effing weird.

[WolfWhistle]

Originally Posted by Taranwanderer

I got it, I've been watching their videos, very helpful and informative. Thanks! And the rig is level.

Now for today's mystery: after it cooled down on gas last evening, I turned the switch over to "Auto" and let it run on electric, figuring that when I went out there this AM, it would be defrosted and warm again and that the electric heating element would be the culprit. NOT SO FAST, JUNIOR. Went out this AM, and it's still cold--like totally working normally. If it's set to Auto, I'm assuming its running on electric only. Is it possible that it just needed to thaw out and then resume working normally? Is it possible that turning off both the 120V AC and the 12V DC supply caused the board to "reset" somehow? I'm really at a loss. The analytical in me is thoroughly vexed--how could it just randomly defrost itself, and then be working fine after cutting power? My next test is to turn it off again, let it warm up to room temp (thaw) and then see if it will cool down on electric only.

This is effing weird.

TCCWLOTW (the old phone guy adage - Trouble came clear while looking out the window.

You would be amazed... I'm certainly am ... at all the devices, high tech things, that will work again after a power-down-and-up reset. After powering down it is a good idea to wait for several minutes. Many times it is the only way to fix things. You can spend hours trouble shooting the thing or reboot. If the trouble keeps coming back, then dig in.
WW

[Taranwanderer]

Well, I'm totally stumped now. Let the fridge off, it warmed up to ambient temperature, then I turned it back on (electric,) and it cooled down just like it's supposed to. I'm reminded of the warden from Shawshank-"It's a miracle! My fridge problem up and vanished like a fart in the wind!" I'm guessing it'll be back at some point, unlike Andy Dufresne. But for now, thanks to everyone who helped out with your suggestions and experience, especially those RV refrigeration videos! I'm still not done viewing all those little gems.

Think I'll go stock the fridge with some beers...

[SidecarFlip]

Don't worry, it will 'show' up on a humid hot summer day when you want a cold beverage and open the door and your beverage is warmer than it is outside...and your food is shot too....

[M&K Hoffman]

Originally Posted by SidecarFlip

Don't worry, it will 'show' up on a humid hot summer day when you want a cold beverage and open the door and your beverage is warmer than it is outside...and your food is shot too....

Unfortunately this is most likely correct. I have added fans, both interior circulating and cooling fans in the roof vent. I have also replaced the thermistor with the "snip the tip" unit. I won't really know how well they work until next year as hot weather is over in my neck of the woods.
I have noticed reading many threads on fridge problems that the DM2652 seems to be especially prone to the problem.

[SidecarFlip]

I believe the trick (if you want to call it that) is keeping the ambient air circulating over the coils on the backside of the unit at the highest rate possible (barring an refrigerant leak) of course, which renders any unit unable to transfer heat (no more cooling).

In that respect some good 12 volt muffin fans (computer cooling fans) and a thermocouple switch are your best friends. Those little fans move lots of air and are very friendly current draw wise.

My Dometic came with one (noisy) fan. I replaced it with 2 quiet ball bearing fans. My Frig runs at least 40 below ambient on the medium setting with the OEM thermisistor centered on the outside transfer fin.

I run a remote (outside of the door) temperature gauge (digital) available from RV Country for about 15 bucks to monitor interior temperature (without having to open the door and letting in warm air.

An absorbtion unit cannot recover as quickly as a compressor type unit, so opening the door to check a temp gauge is counter productive.

[Taranwanderer]

Originally Posted by SidecarFlip

I believe the trick (if you want to call it that) is keeping the ambient air circulating over the coils on the backside of the unit at the highest rate possible (barring an refrigerant leak) of course, which renders any unit unable to transfer heat (no more cooling).

In that respect some good 12 volt muffin fans (computer cooling fans) and a thermocouple switch are your best friends. Those little fans move lots of air and are very friendly current draw wise.

My Dometic came with one (noisy) fan. I replaced it with 2 quiet ball bearing fans. My Frig runs at least 40 below ambient on the medium setting with the OEM thermisistor centered on the outside transfer fin.

I run a remote (outside of the door) temperature gauge (digital) available from RV Country for about 15 bucks to monitor interior temperature (without having to open the door and letting in warm air.

An absorbtion unit cannot recover as quickly as a compressor type unit, so opening the door to check a temp gauge is counter productive.

So you mount the computer fans inside the fridge, or on the backside out where the access panel/"lower vent" is? Do you have a link to said thermocouple switch? I think I have a computer fan around here somewhere, or I may scavenge one from the old DirecTV receiver that I saved for parts for just such an occasion...😉

[SidecarFlip]

The fan goes on the backside (outside of the fridge), not inside. You mount the fan in the upper part of the cavity to force pull the air from the lower access up and out the top vent (or in my case out the upper side vent because my unit has no roof vent.

Just relying on natural draft works but forcing the air movement across the coils in the back improves the efficiency of the system many fold. T'stat wise, all you need is a 100 degree on snap action (bi metal) t'stat attached to one of the coil tubes wired in parallel with the motor. That way, when the coils reach 100 degrees (which they do during absorbtion), the fan or fans (in my case I replaced a single one with 2 (I bought on flea bay) come on and cause a forced draft (air flow) across the coils, transferring heat quicker and better from inside your fridge. Now, if you have an amonia issue (excuse my spelling).., the fans won't help. If you had / have an amonia leak, you'd know it by smell, you'd swear a cat peed in your coach...it stinks.

Conversely, you could wire them to the fridge power switch but then they would run constantly when the fridge is powered up. I like the thermostat setup. When the fridge inside reaches your desired temp, the absorbtion mode ceases and the coils cool and your fan(s) turn off because the coils cooled below 100 degrees. If you wire them into the power on switch, they never turn off because the fridge is always powered up whether it's in absorbtion mode or not.

Mine came with one fan and it worked okay. I canned the noisy single fan and went with 2 ball bearing muffin fans and the cool down time was cut by a third plus it has no issue holding 40 degrees below ambient... and everything in the freezer compartment stays frozen like a rock.

If you make that modification, it would be a good time to add fine mesh metal screening (available in rolls at Lowes to the lower intake panel, upper exhaust panel, your HWH vent and your furnace exhaust to keep unwanted flying insects (aka: yellowjackets) out. The little basturds seem to love RV's. I don't love them at all.

[R3Jones]

I threw this together and the fridge performs much better.



I wired the thermoswitch to the "auto" side of the selector switch and direct to the fan on the "hand" side. This way I can force it to turn on when I want or operate based on temp.




-R.Jones
Nitro 31FQSL

[SidecarFlip]

That works I bet. The trick if you want to call it that is forcing the ambient are to move over the coils instead of relying on natural (cool to warm convection) draft. Muffin fans consume very little current an added benefit.

How noisy are they when operating?

Increasing the rate of heat transfer across the heat exchanger coils increases the cooling efficiency inside the fridge...

[Taranwanderer]

Nice setup, guys. Links to your switches and fans would be awesome...