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Author Topic: Rm1350 refer not cooling  (Read 1401 times)

Coopster8

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Rm1350 refer not cooling
« on: April 25, 2018, 06:27:25 PM »
Hey all,
We are a proud owner of a 2009 keystone challenger, but we're finding out some little (big) problem. Our rm1350 isnt cooling.. the freezer is cold, but the refer is nicely maintaining 50 degrees, i checked the fans, they work, but never heard them come on. I drove it to the camp another camp site an hr away and guess what, it went down to 33😁 well in a couple hrs it was back to 50😭 .
Any advice/suggestion would be great

donn

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Re: Rm1350 refer not cooling
« Reply #1 on: April 25, 2018, 07:28:00 PM »
Clean the chimney.

Coopster8

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Re: Rm1350 refer not cooling
« Reply #2 on: April 25, 2018, 08:14:13 PM »
Clean the chimney?? How is this done?? Im sure i might find in youtube.

donn

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Re: Rm1350 refer not cooling
« Reply #3 on: April 25, 2018, 08:23:49 PM »
Climb up on the roof, take the top cover off.  Using a wire brush scrub the chimney.  Its just like a chimney sweep does for your home.  Follow by blowing all the debris out.  Carefully clean up the crud.  Before you start tape the burner orifice to protect it from being clogged.

Coopster8

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Re: Rm1350 refer not cooling
« Reply #4 on: April 25, 2018, 08:42:52 PM »
Ok thank you, but everything i find on YouTube is if its not working on gas. I have put the thermostat outside to trick it, and it still don't lower in temperature below 50 or so, on gas or electric. I have put a fan on the back fins for a day and still don't drop. The freezer gets cold but the refer dont. I will clean chimney tomorrow, to see if that works. My chimney is dont go though the roof, since my refer is in my slide.
I have jumped the fans as well and ran for a day. The only time it stayed cool was going to new site. (33 degrees) i ran gas only, thinking its control board, still holds at 50 😠, 

8Muddypaws

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Re: Rm1350 refer not cooling
« Reply #5 on: April 25, 2018, 10:33:02 PM »
That it cooled better while traveling is a pretty good indication of poor airflow. 

If the refer is installed in a slide there will be some luan panels to route the hot airflow out the side vents.  If that panel has come loose hot air could be pooling.

If it's not installed in a slide there may still be luan panels.

There will be a thermostatic switch attached to one of the fins on the cooling unit.  If it's not making good contact with the fin that could be part of the problem.  Are you sure the fan(s) are coming on?

Cleaning the chimney is good advice.  Anything, and we do mean anything that blocks the convection airflow is a problem.

Several people on here have added 12v computer fans to draw air through the system.  I'm one of them.  My 1201 LRIM is consistently 34-37F in the refer box and -18F in the freezers.  I used 4 fans and a 180F thermostatic switch to turn the fans on when needed.  My refer is in a slide.

Good luck with it.
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #6 on: April 26, 2018, 11:04:47 AM »
I will install more fans and clean chimney today, also look for the luan panel as well, anything has to be better than what im doing now.. I will keep you updated on the status of the recommendations also the wind theory makes sense..
Hoping for the best

Coopster8

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Re: Rm1350 refer not cooling
« Reply #7 on: April 26, 2018, 05:10:25 PM »
Ok.. 2 more powerful fans installed, i pointed them up towards the fins.. my refer is in the slide, but dont see any luan panel or anything that routes the heat out of my refer compartment. I by passed the thermostat on fins to see if that helps..
I work on chimney this weekend, but will keep you updated

8Muddypaws

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Re: Rm1350 refer not cooling
« Reply #8 on: April 26, 2018, 06:56:02 PM »
From my experience trying to force air through the system is about half as effective as drawing it through with exhaust fans.  If you search on 'Muddypaws Mod' you find my old posts covering everything I did to my refer.
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #9 on: April 26, 2018, 08:02:38 PM »
Another stupid question concerning my problem. The black tank on the cooling system, should it be warm to the touch, or hot to touch? Mine is hot to touch

donn

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Re: Rm1350 refer not cooling
« Reply #10 on: April 26, 2018, 08:45:37 PM »
The cooling unit uses heat to cool.  Yea, it makes no sense.  So yea it will be hot.  Again, like you have diacovered your issue is totally anmair flow issue.

Coopster8

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Re: Rm1350 refer not cooling
« Reply #11 on: April 26, 2018, 08:51:39 PM »
Ok, i have been running new fans for about 5 hrs and no change, still 54 😢 ill see in the morning, im currently running 2 3600rpm 1amp fans, i figured in 5 hrs it would of dropped some..

8Muddypaws

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Re: Rm1350 refer not cooling
« Reply #12 on: April 26, 2018, 09:03:48 PM »
It should be VERY hot!  Like barely able to put your hand on it for more than a second or two.

Well DUH on my part!

If you're running on AC power it may be that one of your two heating elements has gone bad.  It's a simple matter to test them with an ohmmeter.  Check your manual for the proper resistance.  They're not horribly expensive or hard to replace.

This also would explain why it cooled better while traveling.  It's running on propane then.

See page 16 of this manual : https://www.manualslib.com/manual/766001/Dometic-Rm1350.html#manual
« Last Edit: April 26, 2018, 09:08:13 PM by 8Muddypaws »
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Gary RV_Wizard

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Re: Rm1350 refer not cooling
« Reply #13 on: April 27, 2018, 08:44:28 AM »
The boiler tank operates at about 350 F., so yes it should be extremely hot and the vertical tube above it also, though decreasing with distance.  The rest of the tubing on the return side should only be warm.

Muddypaws may have hit on the problem, i.e. a bad AC heater.  The RM1350 uses two 120v heaters in series, so in some failure modes you can lose heating capacity and cooling efficiency drops.  That would explain why it cools well on propane but not so well on 120v electric.  Try it on LP at the campsite and see how it performs.  If LP always works well, you can be confident that air flow, fans, etc. are all working as designed and that the problem is in the AC heater components. Note that low AC voltage to the fridge or a poor wire connection in the 120vac heater circuit would have the same effect.

http://bryantrv.com/docs2/docs/Service%20Manual,%20RM1350.pdf
« Last Edit: April 27, 2018, 08:53:01 AM by Gary RV_Wizard »
Gary
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #14 on: April 27, 2018, 04:49:34 PM »
Oms checked it and reading good, so now have it on l.p. for the night and see how it does.. crossing fingers

Gary RV_Wizard

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Re: Rm1350 refer not cooling
« Reply #15 on: April 28, 2018, 11:03:12 AM »
Did you verify the voltage at the element as well as ohms? There isn't much electronics between the RV's 120v outlet and the heater elements, basically just a relay that turns power on/off, but its conceivable there is a low voltage problem.
Gary
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Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Coopster8

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Re: Rm1350 refer not cooling
« Reply #16 on: April 29, 2018, 09:34:12 AM »
Still nothing, I oms checked heating elements, and it read 37.. which is good.. I'm going to more fans to exhaust today, instead of blow and see if that helps.. I want to thank everyone trying to help me troubleshoot this problem.. sounds like a air movement issue but it's just not bring it down any.. maybe ill just keep drive around to keep temp down..😂

8Muddypaws

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Re: Rm1350 refer not cooling
« Reply #17 on: April 29, 2018, 10:49:30 AM »
Have you checked the thermistor per the troubleshooting steps?  They have been known to go bad.
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #18 on: April 29, 2018, 10:52:13 AM »
Yes, have even changed it.. 1st thing i did.. checked volts on elements.. 119.9 v👍 forcing air out now.. let's see how that goes.

Gary RV_Wizard

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Re: Rm1350 refer not cooling
« Reply #19 on: April 29, 2018, 11:18:52 AM »
Rather than shotgun the problem with more fans, run it in LP gas mode for a day. If it cools ok in LP gas mode, then air flow is not the problem and you need to look elsewhere.  Ditto with the thermister - same one is used whether electric or LP. 
Gary
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Sun2Retire

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Re: Rm1350 refer not cooling
« Reply #20 on: April 29, 2018, 11:20:04 AM »
Rather than shotgun the problem with more fans, run it in LP gas mode for a day. If it cools ok in LP gas mode, then air flow is not the problem and you need to look elsewhere.  Ditto with the thermister - same one is used whether electric or LP.

Gary he already ran it overnight on LP
Scott
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #21 on: April 30, 2018, 10:40:51 AM »
Well sucking air didnt help😢 call service tech, that was a waste of time and money, he had no clue himself. So went out and got a small refer.. had to have something to keep beer cold,😊 while troubleshooting this. Everything you have suggested, I've done..

Gary RV_Wizard

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Re: Rm1350 refer not cooling
« Reply #22 on: April 30, 2018, 11:24:33 AM »
Quote
Gary he already ran it overnight on LP

I missed that (and still don't see it). Just that it ran on LP while traveling.  Since my reading of this topic seems to be deficient, what was the result of running on LP at the campsite?

If it runs fine on LP, both driving and parked, then it is pointless to fiddle with fans and air flow, cause those are identical whether using electric or gas. The only difference between electric and gas modes is the heat source for the boiler. Everything else works exactly the same.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Sun2Retire

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Re: Rm1350 refer not cooling
« Reply #23 on: April 30, 2018, 11:55:17 AM »
I missed that (and still don't see it). Just that it ran on LP while traveling.  Since my reading of this topic seems to be deficient, what was the result of running on LP at the campsite?

If it runs fine on LP, both driving and parked, then it is pointless to fiddle with fans and air flow, cause those are identical whether using electric or gas. The only difference between electric and gas modes is the heat source for the boiler. Everything else works exactly the same.

I got tangled up in the back and forth also, so went back and re-read each entry. On the 27th OP reported he would leave it running overnight on LP, and on the 29th he reported it still doesn't cool. I am confused by the earlier comments that it cooled OK while driving, which started a chase down the airflow path, but now it doesn't sound like that was anything more than an anomaly.

He's already changed thermistor, checked both heating elements, cleaned the chimney, installed a couple different versions of auxiliary fans, and tried it on both LP and electric and it still doesn't work. So if I've followed the story correctly he has a fridge which, on both LP and electric, marginally cools the freezer but won't get the fridge portion below 50, which in my much less learned than you opinion sounds like a classic cooling unit failure.
« Last Edit: April 30, 2018, 12:54:27 PM by Sun2Retire »
Scott
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Rene T

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Re: Rm1350 refer not cooling
« Reply #24 on: April 30, 2018, 12:21:38 PM »
I missed that (and still don't see it).

He mentioned it in Reply#14 and came back on Reply#16 and said it still didn't work.
« Last Edit: April 30, 2018, 03:42:59 PM by Rene T »
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #25 on: April 30, 2018, 03:40:30 PM »
Sorry about all this confusion. I'm just trying to get this fix.. so ill repeat all that has happened and I have done.
I started camping ft, and the refer is maintaining 50, so i changed the tremisor, and no change. After trying a couple things, I came to here and started asking questions.
Then I had to drive it to carpenter campers, for something else(they couldn't look at it)(about an hr total drive time) the temp dropped to 33 so then the thread started

. I have installed new fans to blow, ran on l.p. only, cleaned chimney, moved fans to exhaust instead of blow. I have oms checked heating elements, volt check everything and all the good, except the temp never goes below 48 that makes the freezer 26

I hope this clears up the confusion, if the cooling unit is bad, then wouldn't not cool to 33 while driving??

Sun2Retire

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Re: Rm1350 refer not cooling
« Reply #26 on: April 30, 2018, 03:55:00 PM »
if the cooling unit is bad, then wouldn't not cool to 33 while driving??

I would have to agree, but the fact that no matter how much air is moved and all the other things you've tried it now won't cool either the freezer or the fridge properly (at mid range setting the freezer should at least be in low single digits and the fridge should be in the mid 30s, give or take).

What is the longest the unit has sat running without the doors being opened a single time?

Also, have you checked the seals on the doors? Open the door, then close the door on the bill. The door should grab the bill. Check the entire seal all around all doors.

What is the outside temp where you're located?
Scott
Fulltiming in a 2005 Newmar Dutch Star 3810, Spartan, Cat C7 350
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Coopster8

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Re: Rm1350 refer not cooling
« Reply #27 on: April 30, 2018, 04:03:21 PM »
The longest is has set without doors opening is approx 15hrs.
Doors checked like stated
In pensacola fla, temp is approx 73 day, 55 lows at times.
Also looking at getting a new cooling unit, and i see that they have insulation around the pipes.. mine dont have.. should they??

kdbgoat

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Re: Rm1350 refer not cooling
« Reply #28 on: April 30, 2018, 07:41:27 PM »
How are you checking the temperature in the fridge? If using a normal thermometer, the temperature will rise immensely as soon as you open the door. Use a pocket thermometer in about an inch of water in a glass, or a temperature sensor with a remote wireless readout.
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regval

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Re: Rm1350 refer not cooling
« Reply #29 on: May 01, 2018, 12:07:09 AM »
I know that others have offered opinions on possible solutions so I'm not adding to those.
Below is a link to a YouTube video from a RV refrigerator professional that demonstrates how to determine if the cooling unit is functional by bypassing the electronic controls and using the 120VAC heating element of the refer only by rigging a direct connection to Ac voltage. Of course, it has the basic caveat that the refer must have adequate ventilation, be level, etc.

https://m.youtube.com/watch?v=k2bBSGuwU_o
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