Re-thinking the RM8551 4.3

[Ron in BC]

Originally Posted by MyronL

Dave1 just sent me this picture of the back of his RM8551 4.3. Interesting to note he got it with only one fan, and his motherboard is on the back instead of on top like mine is.

I have the same one fan set-up. The one thing that I didn't do when I did all my mods was put in a manual switch. Never heard the fan come on for several hot days. Decided to get that switch installed and then I heard the fan running. I was a little suspicious of why it suddenly started running because the temperatures weren't even as high as when it hadn't run.

Looked up at the vent and discovered the adhesive holding the reflectix that I'd put in the vent cap had let go and it had dropped down and effectively closed off the vent. Pulled it out and fan hasn't come on since. So, manual switch it is.

Ron

[MyronL]

I just listened to my 2 fans running for a solid two minutes. Right now it is 97° F inside the trailer. Now wondering maybe don't need to add that nice rocker switch (7/16ths inch hole) for manual fan control.

Oh... and the current temperature inside the fridge? Sorry, that info not ready for prime time yet.

[cpaharley2008]

I know, you are going to wait until tomorrow night, when the debate is on tv and post your results....not fair.

[dave1]

Originally Posted by Kountrykamper

From my experience ours seems to cool better just running the lower fan. Pat installed a better quality fan than I did so maybe it will do something mine don't. With just the lower fan running I can feel a draft coming out of the roof vent when standing on a ladder and holding my hand next to it.

It would not hurt to install it while you have the fridge out. May give you more options.

Good to know with one fan running you can feel air movement at the top vent. I will install a fan in the cavity area since the fridge is out.
Thanks again for your reply and to all who are taking the time to post their efforts to get this fridge working.

Dave

[Tonny LR]

Originally Posted by MyronL

Dave1 just sent me this picture of the back of his RM8551 4.3. Interesting to note he got it with only one fan, and his motherboard is on the back instead of on top like mine is. Does not leave much space for adding a second fan.

Fan placement could be crucial for best efficient fan cooling. Wondering if all with same as this have made changes and if they are working for you.

Hello Myronl and Dave,
I have two Texas fans which were controlled by a fan switch in the rear installed by ETI. The lower fan situated at the same loacation as Dave's lower fan. The lower fan did not start when inside trailer temperature was above 90F. It appeared that there is a thermastat controlling the fans too because the upper fan stopped when the temperature was in the 70s F. Please offer your assessment as to why the lower fan did not come on? Is it defective? Thanks.

Tonny LR

[dave1]

Originally Posted by Tonny LR

Hello Myronl and Dave,
I have two Texas fans which were controlled by a fan switch in the rear installed by ETI. The lower fan situated at the same loacation as Dave's lower fan. The lower fan did not start when inside trailer temperature was above 90F. It appeared that there is a thermastat controlling the fans too because the upper fan stopped when the temperature was in the 70s F. Please offer your assessment as to why the lower fan did not come on? Is it defective? Thanks.

Tonny LR

Tony,

I'm a bit confused. You say you have two Texas fans on a switch installed by ETI, are they in the baffle area? The fan in my picture is a stock fan provided by dometic. This fan has never come on. It appears the thermostat has a very high set point. I will put a switch on it so I can turn it on and off.

Dave

[Tonny LR]

Hello Dave,
The fan in your picture in the baffle area is the fan that i am addressing. It never came on when it was hot. I assumed that it was installed by ETI when I ordered Texas fan. I did not realized it is a Dometic stock fan which have a very high thermostat temperature setting. Thanks for clarification. I installed a two speed computer case fan at the base floor and plug into the the 120v outlet installed by ETI located at the baffle area. It worked well. I used the low speed during the night and could not hear any noise at all. Thanks for providing refrigerator fan education.

Tonny LR

[MyronL]

Hot outside the last few days. The trailer sat in full sun. I think Wednesday’s results are gratifying, considering the very high trailer interior temps and 4.3’s predictably slow cooling performance. (No, I never opened the door.) Thursday’s results are telling in that the fridge never got warm as 40°F, a good thing. Should also mention I had removed the freezer compartment.

My fans did come on periodically. Thinking a fan thermostat that governs with a lower threshold, like 130°F, is a better idea, so shall replace fan factory install. I will add a manual switch to give me fan control on demand. Seems logical, if speedy heat evacuation is the key to cooling performance.

[dave1]

Ready to wire a switch for my single fan. Looking at the thermostat to add wires for the switch, there is a clear end and a black end both with red wires. Does it matter which color end wire goes to power side of the switch.

Thanks

Dave

[MyronL]

Once the smoke clears, be sure to take a picture of the connection, Dave

[Kountrykamper]

Originally Posted by dave1

Ready to wire a switch for my single fan. Looking at the thermostat to add wires for the switch, there is a clear end and a black end both with red wires. Does it matter which color end wire goes to power side of the switch.

Thanks

Dave

No, it does not matter.

[Jubal]

Originally Posted by dave1

Ready to wire a switch for my single fan. Looking at the thermostat to add wires for the switch, there is a clear end and a black end both with red wires. Does it matter which color end wire goes to power side of the switch.
Thanks
Dave

http://www.escapeforum.org/forums/f3...ng-5344-9.html
post 84

[Ron in BC]

This is where even the cheapest of volt meters is your friend. With one you can put one lead to ground. Then test the wires in question. The one that's hot is the one that will also go to the switch. The other side of switch goes to the other wire. You're hooking the switch up in parallel. Either the thermostat or the switch can turn on the fan.

Ron

[dave1]

Jubal,
Thanks have seen that post and read it, my question is does it matter which wire goes to which terminal on the new switch.
Just saw kountrykampers post that it doesn't matter.
Thanks all for the help!
Dave

[MyronL]

Is this correct? (I added the little 5 amp fuse that came with the new cooling switch therm, and the toggle switch has a third spade I assume is for ground, which I have ignored.)

[cpaharley2008]

That works on my unit, wired similarly. If you did ground your switch it may illuminate?

[MyronL]

Ah, the deed is done! Everything seems to work (after several blown fuses, wrong connections, panicky thoughts, etc.) Right, Jim, light on the rocker switch finally came on after I grounded it.

[I eliminated the in-line fuse.]...............Hope this pix is not too confusing.

Now begins round 2 of fridge cooling performance testing.

[Kountrykamper]

One thing Myron if I'm following your picture correctly. It looks like a wire is touching the flue exhaust or very close. I would push it away some so it don't melt and short if your running on propane.

[MyronL]

Well I don't know but now I'm thinking something ain't right. Just stepped out to the trailer and the fan is still running. It has been running non-stop since I started this round of testing at 3 PM.

Been 5 dots on shore power all afternoon. Currently, 7:30 PM, fridge temp is 46°F and trailer temp is 86°F. At 3 PM fridge temp was 57° and trailer was 89°. A drop in temp of 11 degrees after 4½ hours ain't so great, that's for sure. I sat in the trailer from 6:30 to 7:30 PM and the fan never stopped running.

The re-thinking continues.

[MyronL]

7:30 AM-- just checked and the fridge temp is 33° trailer temp is 60° and, the fan is not running.

Of course I then used the switch several times and that turned the fan on and off like it should.

This seems to indicate yesterday's issue has more to do with the new 130° fan thermostat not willing to shut the fans down early like I was expecting, because it thinks things aren't cooled down enough back there.

Guessing biggest issue now is constant fan whine and/or DC drain if boondocking. I'll just wait things out awhile before deciding to go back to the original fan thermostat or not.