Dometic freezer cold but fridge barely gets to 60 over night

[arcsum68]

Hey all,

My wifes family owns a classic houseboat and the fridge has been driving us nuts trying to figure out why it will not work correctly. I believe its an RM3600 series and the thing works great when it goes into the shop, but in real life it is worthless. It also works much better when plugged into the generator, but that is not really sustainable. Being in a HB it only gets turned on when we get there and off when we leave. It will pretty quickly get the freezer cold and that will definitely freeze water bottles, but the fridge part is not even close to food safe. I have added fans, gone through all the maintenance including buying the specialized brush, and even bypassed the propane line so its on a dedicated tank.

Is this thing a dud or is there hope? Any suggestions? I have seen rebuilt cooling units out there, but I am not sure that is the issue since the freezer does work so well.

[arcsum68]

* I never would have guessed more room would be an issue, in fact in trying to see if it was TOO little space I actually pulled it out from the wall a few inches thinking it would have more room to breath (as a test). Great info, thanks!

[arcsum68]

Its a 1976, nothing was made big in this thing. There is the typical amount of space behind the fridge as you would expect in any typical RV. It has the upper vent and the lower panel vent. The fridge is flush with the cabinetry on the front and fits exactly into its cavity with the exception of the top.

[wolfe10]

Correct-- too much space at the back allows turbulence vs laminar flow over the condenser. In fact correct MAXIMUM space is as or more critical as correct minimum space.

All this is covered in the refrigerator installation manual.

[shastagary]

I checked those clearances as well and still believe we have plenty of room

you do not just want just plenty of room you do not want a 8 inch gap at the back of the refrigerator it needs a smaller gap to force the cooling air through the cooling coils or baffles to force it through the coils keeping the burner side hot and the cooling coil side as cool as it can be otherwise the air coming in can just bypass the cooling coils not cooling them as good as it should reducing efficiency .

[arcsum68]

shastagary wrote:
if it actually worked good on the test bench then you may suspect the installation and proper parameters of the venting and how close it is mounted to the outside wall to get a proper cooling chimney effect.
is one of the vents on the cabin roof or are they both on the side wall?


the manual describes the parameters dometic rm 3600

Based on the PDF we are in clearance tolerance for height, also I have active fans blowing air up and out. I have also removed the top cover just to remove any restrictions, this obviously did not help.

Update, I believe it is a Dometic Americana RM2652 or RM2852. I checked those clearances as well and still believe we have plenty of room. Sorry for not knowing exactly what it is, if it were mine I would be well versed. Due to multiple issues I had not been on the thing in 2 years until last weekend and it sparked my desire to either figure it out or at least reclaim the space.

[arcsum68]

btcruzer wrote:
You might want to check out another post in this tech issues called dometic refrigerator woes....

On it, thank you!

[wolfe10]

Yup, clearance dimensions as outlined in the installation manual are CRITICAL to proper cooling performance.

And, muffin fans on top of the condenser blowing UP improve performance.

[shastagary]

if it actually worked good on the test bench then you may suspect the installation and proper parameters of the venting and how close it is mounted to the outside wall to get a proper cooling chimney effect.
is one of the vents on the cabin roof or are they both on the side wall?


the manual describes the parameters dometic rm 3600

[btcruzer]

You might want to check out another post in this tech issues called dometic refrigerator woes....

[arcsum68]

dougrainer wrote:
If it has been to the "shop" and they state it is good, WHAT ARE THE TEMPS THE SHOP REPORTED? The ONLY test for the lower section is a glass of water after 24 hours with the 120 element wired direct to 120 volts. THIS will tell you the condition of the cooling unit. The FREEZER will get extremely cold within a few hours but the lower section will take 24 hours. 24 hours is the required time. NO SHORTCUTS. If you have had the refer in the shop and told them about the failures, they should have told you the water temp after 24 hours hot wired. The Freezer should be 0 to 10 degrees after 24 hours. The lower section the water in the glass should be at least below 36 degrees. 36 to 40 is marginal and indicates a partially block Cooling unit. Anything above 40 degrees the cooling unit is blocked enough to prevent adequate cooling. Make sure the AC line voltage is above 115 volts. Doug

Hey Doug, it was my father in law who took it to the shop and he probably didnt ask them and I never knew to ask him. I will say the thing seems to cool down when the generator is running (that is the only 110 we have), but even having it plugged in and on AC when the generator is running it will still never get cool enough to be usable because we only run the generator at most a few hours at a time. We are at Oroville Lake in Northern CA, yes it gets hot, but there are TONS of people out there with propane refers that do not have this issue. If its the cooling unit, so be it, but I do not want to entertain replacement if this is going to just be the same issue with a new unit. Sure wish I could pull it again to see the results of that 24 hr test. Might be time again, maybe it just doesnt go back in. I just ordered 400watts worth of solar, maybe we just put a regular fridge in there and run it off the inverter, sucks though because that would probably put us equal to where we were other than the batteries being topped off when we get there.

[midnightsadie]

listen to doug he knows his stuff. .

[dougrainer]

If it has been to the "shop" and they state it is good, WHAT ARE THE TEMPS THE SHOP REPORTED? The ONLY test for the lower section is a glass of water after 24 hours with the 120 element wired direct to 120 volts. THIS will tell you the condition of the cooling unit. The FREEZER will get extremely cold within a few hours but the lower section will take 24 hours. 24 hours is the required time. NO SHORTCUTS. If you have had the refer in the shop and told them about the failures, they should have told you the water temp after 24 hours hot wired. The Freezer should be 0 to 10 degrees after 24 hours. The lower section the water in the glass should be at least below 36 degrees. 36 to 40 is marginal and indicates a partially block Cooling unit. Anything above 40 degrees the cooling unit is blocked enough to prevent adequate cooling. Make sure the AC line voltage is above 115 volts. Doug

[ksg5000]

Always thought that RV fridges are pretty much the same. One cooling unit where cooling starts in freezer and works it's way down. Threads that indicate that freezer is working but fridge doesn't tend to be resolved with time/patience. Maybe houseboat use puts more pressure on fridge than RV where you can allow everything to cool down on driveway b4 taking rig out?

[arcsum68]

wolfe10 wrote:
Sure, it could be a cooling unit. But it would not have been exposed to the #1 killer of absorption cooling units-- being run out of level.

At least we hope on a houseboat (not a sailboat) that it has been level when it is on!

Assume you have confirmed propane pressure (11" W.C). Low pressure results in low flame= poor cooling.

LOL, yes it has always been level, as a 52' HB tends to be. I actually built a manometer to check for pressure and just to be absolutely sure that was not the issue I installed a BBQ style regulator and have an extra tank within a foot of the fridge. It's getting very good pressure.