Muffin Fan Installation Norcold 1200LRIM

[Executive45]

It is imperative that the cooling units on the Norcold 1200LRIM get proper ventilation. These units are shipped with two muffin fans mounted on top of the coils. Drawing air upward over the coils is more efficient than blowing air upward from the bottom. The problem arises when outside temps skyrocket. The coils heat up and the cooling process diminishes. Often, the OEM muffin fans are inadequate to keep up or they fail altogether. To access these fans, the fridge must be pulled part way out and even then it's a pain. My solution to these issues was to buy and mount additional fans and put them where I could easily access them if they were to fail. My two OEM fans pulled 45cfm ea.

I purchased four of THESE fans @ $4.25ea. I also purchased a new snap switch to control the fans although they really could run 24/7. These button switches are available on Ebay, package of three for $5.15 free shipping. Finally, I purchased two 48" pieces of 3/4 angle aluminum stock from Home Depot at $6.15 ea. Mounting screws are a personal choice, but I chose 2" stainless steel hex screws with nylon lock nuts. Package of two @ 98 cents/ea.

Below are some pictures to assist if you decide to follow my footsteps. It took me about 1 1/2 hours the first time and about an hour the second time. Originally I mounted the fans flush with the roof line but the hum resonated through the coach so I disassembled everything and redid it lowering the fans further into the flue opening.....PM me if you have any questions. Hope this helps someone....Dennis


Up on the roof, this is what you see.

After removing the shroud, there is a plastic mesh covering

Remove the plastic mesh covering

I removed the fans I had installed a few weeks ago

Using scrap left over from making the fan holder, I made 4 legs

Remounting the fans using the new legs prevents the sound from resonating in the coach

The beige plastic cover you see in the pictures is for my solar panels. The wiring runs down the side of the refrigerator compartment. I used this wiring loom to run my 12VDC wiring for the muffin fans. I now leave my fridge on 3 and keep the box temp around 38 degrees and the freezer below zero. In 100+ outside temps I kicked it up to 5. IMHO, this is a simple, inexpensive way to enhance the performance of your Norcold. Also, if I have any problems with these fans, they are readily accessible......Dennis

[John_Joey]

Something else to think about, when I bought my old rig I took the top off and also the side access panel. Went up on the roof and using my leaf blower on low, shot air down the shaft. Could not believe how much road dirt came flying out of the access panel. Did it again a few years later with the same results.

Funny how we clean the coils on a S&B fridge for better efficiency, but never think about it on a RV. I shot the air down the shaft with the idea that it was a way of "back flushing."

[Argosy24]

tahiti16 wrote:
Sully the heat transfer isn't more efficient the pulling of the air is. By pulling you are forcing the air up through the coils, when pushing any open area or obstruction greatly reduces the effect of the air flow.

Once the air is in motion what difference do obstructions make if the air has been pushed or pulled to get it in motion?

The air is going to take the path of least resistance in either case.

[moisheh]

Some of the replies remind me of the saying" no good deed goes unpunished": Dennis, you did a great job and I sure appreciate your sharing this idea. I came a cross something similar in an obscure forum. Forum members found a surplus fan system that consisted of multiple smaller fans mounted in a frames . They had the same success as you did. Thanks again.

Moisheh

[rooster2]

This is an great idea and job well done. My next project! Thanks for including some good pictures.

[shooted]

Hi Dennis,
Great job and thank you for the documentation and sharing with us. I am curious if relieving the brackets some would assist with overall cfm. The bracket intrusion into this area (fan opening) might also cause turbulence and a resonance issue. When zooming in on the last picture it appears the brackets are intruding considerably into the fan openings, maybe as much as 40%? Dennis

[Airstreamer67]

I use the "push" method from the bottom simply because it is less of a hassle to set up and maintain. It works for me.

Are there any side-by-side comparison studies to show if one method is better than the other?

Surely the point about the top fans and braces causing less air flow if the fans are not working seems a good one.

[tahiti16]

Sully the heat transfer isn't more efficient the pulling of the air is. By pulling you are forcing the air up through the coils, when pushing any open area or obstruction greatly reduces the effect of the air flow.

[Sully2]

Drawing air upward over the coils is more efficient than blowing air upward from the bottom.

Id sure love to hear the theory of heat transfer you base that statement on??????

And between the fan(s) cages and fan blades...your blocking one heck of a lot of area that by doing so hampers you

[crcr]

Thanks for posting this. I will probably look into this mod in the off season, as my TT fridge doesn't cool as well as I would like.

One question, what are the dimensions of the muffin fans you bought? I don't see that spec at the link you provided.

Edit -- nevermind, I see now the dimensions there in mm.

[Executive45]

bob213 wrote:
Where does that wire running out of the cover go to? Where do you pick up you 12V DC? That's got to be a great improvement in air flow! Nice job.

Bob, those wires are from the solar panels on the roof....they run down through the fridge cutout....Dennis

[Mainship]

bob213 wrote:
Owners who never camp in 90 to 110 degree temps will have much better cooling and won't understand the need for fans. Refrigerators in slide outs seem to have more problems due to the lack of venting. Each is different. I have every cooling "helper" known to man and still struggle in our 100+ degree weather, but it is better than the last TT we had!

Add to that parking in the sun with reefer in the afternoon sunny side. Then there is the time door is open to get to the beer or sodas, many with kids have a separate cooler relieving the reefer of traffic. Using indoor outdoor thermometer tells the story without opening to check.

[bob213]

A lot of the problems related to RV refrigerators is the venting. Too much space or too little space behind the unit will change the draft created. Each builder installs them a little different. If yours is installed with optimum venting it will work great. If not, you will need fans to help it. Owners who never camp in 90 to 110 degree temps will have much better cooling and won't understand the need for fans. Refrigerators in slide outs seem to have more problems due to the lack of venting. Each is different. I have every cooling "helper" known to man and still struggle in our 100+ degree weather, but it is better than the last TT we had!

[Carvin_Marvin]

Thanks for the great pictures. Marv

[Executive45]

Dave, try this...get yourself a small A/C fan, something like the Honeywell turbo fan from WalMart..you probably have one around the house...remove the outside fridge access door and bungee cord the fan so the air is blowing up across the cooling unit. Turn your fridge on and see how quickly it cools down. If you see no change, then perhaps you don't need the fans. If you do, this is a cheap fix..and it looks much better than the fan and bungee cord...:B....Dennis

Why do we need fans when we didn't before?

There's a number of reasons...your fridge is bigger than the one your parents had...there's also the fact that the coolant we used before cannot be used today..remember freon in your automobile's A/C...??? cleaner healthier air means changes...Dennis