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Topic: 'Frig warming up on the road (Read 37 times) previous topic - next topic
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'Frig warming up on the road
Yahoo Message Number: 147371
Hi John. Unlike a cooler an unpowered absorption refrigerator could warm up  20 degrees rapidly. A cooler could have more insulation, and doesn't have a  working fluid. The refrigerator, if the flame had blown out, would have  ammonia liquid transferring heat from the outside in. I think you mentioned  having an internal fan. They consume small amounts of power, but that power is  still dissipated inside, and the cooling unit has to overcome that heat. Check  to make sure the light is really going off when the door is closed. You could  switch the 'frig to electric with no electric (or turn off the propane, but  leave the 'frig on) at home and watch to see how much it warms up just sitting  there. Or even drive it around. I assume the check light doesn't come on.
I might try an inverter running the 'frig on electric while  driving. (engine alternator providing the 12 VDC.) to see if is still warming  up. You can stick a cork in the drain line from the inside drip tray temporarily  to make it a truly air tight box. I'm sure you've checked the door seals for air  leaks. A three year old refrigerator shouldn't be having these problems. Hope  this is helping....RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: 'Frig warming up on the road
Reply #1 –
Yahoo Message Number: 147372
Check  to make sure the light is really going off when the door is closed.
  • It is. I've checked that. Not a source of heat.
I assume the check light doesn't come on.
  • Correct

 You can stick a cork in the drain line from the inside drip tray temporarily  to make it a truly air tight box.
  • Tried that with a small "C" clamp to completely choke off any potential backwards airflow at the end of the drain hose - still heats up.
I'm sure you've checked the door seals for air  leaks. A three year old refrigerator shouldn't be having these problems.
  • Agreed!
Hope  this is helping....RonB
Re: 'Frig warming up on the road
Reply #2 –
Yahoo Message Number: 147373
John and Ron,
 I have seen the same warming fridge problem on my '05 MB and can tell you what works for me.  The solution came from an independent RV fridge service guy near Charlotte, NC.
 His thinking is that depending on the geometry of the RV roof relative to the air flow caused by RV motion and the relatively short "chimney" between the top of the fridge and the roof vent cover an "air dam" is developed which effectively stops the air flow through the cooling coils in the back of the fridge.  No flow from the bottom of the fridge through the coils and out the roof vent, no cooling.
 The height of the chimney is factor because a upward draft does not get much of a chance to be developed.  The tall chimneys you see around factories are there just for that improved draft.  LDs are short as RVs go.
 The solution is a 12 volt desktop PC muffin fan at the top of the "chimney" just under the roof vent cover.  The fan runs to evacuate the air below it.  The muffin fan is controlled by a thermostat mounted on the stovepipe above the gas flame (and electric heater).  The idea is to run the fan only when there's heat and the cooling unit is operational.  This is what was installed by the RV fridge service guy and it works!
 I added an in-line ON/OFF switch to disable this fix.  It makes no sense to run it when you're camping and it just drains your house batteries.
 I do not use a fan inside the fridge.  While it may even out the temperature inside or increase the fridge duty cycle making it cooler, it otherwise adds heat inside the fridge.

Alex Rutchka, SE #4
Re: 'Frig warming up on the road
Reply #3 –
Yahoo Message Number: 147375
I did buy but never had installed a fan as you describe. I've done so many other things I might as well try that. What doesn't make sense to me is if this is the problem, how come others aren't having the same trouble?

John A Wozniak
Re: 'Frig warming up on the road
Reply #4 –
Yahoo Message Number: 147379
John,

The problem is not unique to you and me and has been brought up in the past.  So there are others. Also, some people may have it, but be oblivious to it.  How many look at the fridge's inside temperature while traveling?

But, there are a number of variables involved and perhaps most folks get a pass.  It's not exactly a black and white thing and mostly comes in shades of gray.  But, at some point, with the cooling unit duty cycle at 100%, it is not enough.

In my case, the fridge is immediately behind the driver.  That positioning may be one factor.  Outside windiness may make a difference.  Travel speed definitely makes a difference.  I had not seen the problem below say 50 mph. Outside temperature is clearly a factor because of the relative difference of air density around the coils and the outside.  I'm thinking it has to be warm, perhaps over 80 degrees F outside to have a problem.  Heck, for all I know, the size of the driver side mirror makes a difference in the Bernoulli effect at the fridge's outside panel.

Incidentally, according to my fridge service guy not all those fan kits are very good.  Some do not have efficient motors with ball bearing mounts.  As I said, he selected fans intended for desktop PCs.  He bought them by boxfuls.

Alex Rutchka, SE #4 '05 MB
Re: 'Frig warming up on the road
Reply #6 –
Yahoo Message Number: 147385
From: lifewithalazydazerv@yahoogroups.com [mailto:lifewithalazydazerv@yahoogroups.com]
 Sent: Monday, July 14, 2014 5:46 PM
 To: lifewithalazydazerv@yahoogroups.com
 Subject: [LD] Re: 'Frig warming up on the road

Hi John. Unlike a cooler an unpowered absorption refrigerator could warm up 20 degrees rapidly. A cooler could have more insulation, and doesn't have a working fluid. The refrigerator, if the flame had blown out, would have ammonia liquid transferring heat from the outside in. I think you mentioned having an internal fan. They consume small amounts of power, but that power is still dissipated inside, and the cooling unit has to overcome that heat. Check to make sure the light is really going off when the door is closed. You could switch the 'frig to electric with no electric (or turn off the propane, but leave the 'frig on) at home and watch to see how much it warms up just sitting there. Or even drive it around. I assume the check light doesn't come on.
I might try an inverter running the 'frig on electric while driving. (engine alternator providing the 12 VDC.) to see if is still warming up. You can stick a cork in the drain line from the inside drip tray temporarily to make it a truly air tight box. I'm sure you've checked the door seals for air leaks. A three year old refrigerator shouldn't be having these problems. Hope this is helping....RonB

[Non-text portions of this message have been removed]
Re: 'Frig warming up on the road
Reply #7 –
Yahoo Message Number: 147398
"Incidentally, according to my fridge service guy not all those fan kits  are very good.  Some do not have efficient motors with ball bearing  mounts.  As I said, he selected fans intended for desktop PCs.  He  bought them by boxfuls."
 Bumper's method of mounting two computer muffin fans in the vented door, shrouded in a plenum, is probably the most efficient way to vent the refrigerator compartment.
Free hanging fans, mounted at the top of the vent stack lack the efficiency that shrouded fans do.
It can be a cheap project if you have removed and saved the cooling fans from dead electronic devices. A plenum can be made from several types of materials, such a sheet metal, stacked wood strips or plastic.
Computer fans are made to run for thousands of hours and are usually well sealed.
Some of the vent kits I have seen use fans similar to cheap, little bathroom fans that LD once installed, before Fantastic sold a one-way-only fan. I wouldn't expect them to have as long a life nor flow as much air as a computer fan.
 The fans can be powered by switched 12-VDC or a separate small solar panel that powers the fans during daylight hours only.
The same daylight operation could be added to an existing solar system by running the fan's power wires to inlet side of the solar controller, so they receive power directly from the panels. When the sun goes down, the fans stop running. A dropping resistor may be necessary to lower the panel's 17-18-VDC output to around 13-VDC. Not sure how high a  voltage a computer fan can safely operate at. I would experiment with an old computer fan before buying new.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: 'Frig warming up on the road
Reply #8 –
Yahoo Message Number: 147400
Bumper's method of mounting two computer muffin fans in the vented door, shrouded in a plenum, is probably the most efficient way to vent the refrigerator compartment.

Is there a picture of this somewhere?

John A Wozniak
Re: 'Frig warming up on the road
Reply #11 –
Yahoo Message Number: 147418
http://i674.photobucket.com/albums/vv107/bumperm/Lazy%20Daze/IMG_0934_zps27e8b66b.jpg

http://i674.photobucket.com/albums/vv107/bumperm/Lazy%20Daze/IMG_0932_zpse57cba22.jpg

http://i674.photobucket.com/albums/vv107/bumperm/Lazy%20Daze/IMG_0936_zps46dc040e.jpg

The square PV panel powers the two muffins on the exterior fridge door, the round PV panel is on a marine vent - not shown under is a rubber tube that extends down to the top of the cooling coils.

http://i674.photobucket.com/albums/vv107/bumperm/Lazy%20Daze/IMG_0935_zpsac95ae5e.jpg

http://i674.photobucket.com/albums/vv107/bumperm/Lazy%20Daze/IMG_0937_zps8f8eef66.jpg

And unrelated, the TurboKool install where the Fantastic Fan used to be on my MB

bumper
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: 'Frig warming up on the road
Reply #12 –
Yahoo Message Number: 147423
With all my devices I am getting a page not found error on all of Bumper's links. Even when I break them up, can anyone repost a link that would work. Thank

Sent from Garry's iPhone
Re: 'Frig warming up on the road
Reply #15 –
Yahoo Message Number: 147445
Bumper, where did you get the muffin fans already mounted in the rack? It looks in the photo like they are already racked up and pointed at an angle. That would make the job of plenum fabrication a much easier task than just buying two loose fans.

Thanks!

Charlie
Re: 'Frig warming up on the road
Reply #16 –
Yahoo Message Number: 147446
Bumper, where did you get the muffin fans already mounted in the rack?"
 Bumper undoubtedly bent up the sheet metal plenum in his shop, instead of buying it.

Why buy when you can make it yourself? Anyway, I have never seen a this type of refrigerator fan sold in a package kit.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: 'Frig warming up on the road
Reply #17 –
Yahoo Message Number: 147451
Thanks Larry. I get that he fabricated the plenum from sheet metal. What I was referring to is that the two fans appear to be mounted in a plastic housing that made the plenum job a lot more straight forward.

Charlie
Re: 'Frig warming up on the road
Reply #18 –
Yahoo Message Number: 147459
That's right, I salvaged the two muffin fans from a small Peltier solid state cooling unit used for a wine cooler. They were mounted on a plastic affair that was mostly unsuitable to use as is, I cut off bits and flanges so it would fit in place. It would be almost as easy to mount two fans on some plastic (lexan sheet etc). Thin plywood would work too, just have to paint it.

The balance of the plenum was made from aluminum flashing, the thin .015" stuff you can buy in a roll at Home Depot, normally used for roofing etc. Easy to cut with a scissors (not the ones the wife uses for sewing), and soft enough to bend by hand using a scrap of wood or table edge to bend a straight line (yes, I cheated and used a press brake at my shop :c).

bumper
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: 'Frig warming up on the road
Reply #19 –
Yahoo Message Number: 147460
A bit more on the exterior muffin fan mount:

On the inside of the exterior fridge vent/door, there are two vertical aluminum reinforcements that are 7-5/8" apart. This makes it easy to mount two 3-1/2" to 3-3/4" side-by-side between these reinforcements. The Muffin fans can be mounted to a flat plate with suitably sized holes in it, or can be mounted to two strips of material (bar stock, sheet, etc) one at top and bottom. Alternately, the fans might even be joined with a couple of nylon ties by threading the tie through the fans flange mounting holes.

I sealed the little gaps on my mount with butyl rubber tape (this is moldable, sticky, rubber caulk that doesn't dry out and is handy to have around for all manner of chores). This tape was also used to mount the aluminum flashing plenum where it overlaps above the door louvers (I didn't want to drill the door for fasteners through to the outside so as not to disturb the painted finish).

Hope this helps those who choose to do this project, with the innovative sorts we have on this list, I'm sure someone will come up with an even better or easier way to do this in short order!

bumper
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: 'Frig warming up on the road
Reply #20 –
Yahoo Message Number: 147464
C'n I put a picture directly into a post now?  Well, gonna' try.

This is a fan apparatus that my husband made to go on the outside of the refrigerator.  We haven't tried it out yet.  This is a 2005 RB.



He came down sick right after having finished this last fall, so never got around to doing the write up that he had planned so that I could post this picture.  If anyone thinks he would be interested in knowing more about this, let me know, and I'll prod him with a long stick.

Virtual hugs,

Judie http://dorrieanne.wordpress.com