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Old 03-30-2015, 08:49 AM   #1
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Making a Truckfridge Quieter (and isotherm and Vitrifrigo)

I've got a TF49 truckfridge but this modification should apply to other TF/Isotherm/Vitrifrigo models.

My fridge is still sitting in my garage, not installed yet.......but I can already tell that the fan noise will keep me up at night.

The stock fan (yours may be different depending on when your fridge was built) was a Costech D12A04lws 120mm Fan is rated at :

71.74 CFM
34.4 DB
0.242 Amps
Sleeve Bearing

I sourced a replacement fan from Mouser and it is a lot quieter than the stock unit, it's a Sanyo Denki P/N 9S1212L402 rated at 17db.

48 CFM
17db
Ball Bearing

Both fans are 120mm x 120mm x 25mm, so it's a simple bolt-in deal....roughly a 1 banana job as far as technical challenge. You just need to crimp on some 1/4" faston terminals to the new fan.








There are several threads on theSamba forum about fan retrofits; here is the one that has lots of good info:

http://www.thesamba.com/vw/forum/viewto ... ?p=6338887

There are a few other good choices like the Noctua, Silverstone, etc that will also be significantly quieter than the stock Costech.

I have not done any scientific measurements, but the new fan is almost inaudible and the fridge duty cycle appears to be the same......
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Old 03-30-2015, 09:02 AM   #2
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

Man, mine is dead quiet as is. If you're a really light sleeper you may not be able to stand a pop top anyway!

Anyway, don't mean to hijack.
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Old 03-30-2015, 09:02 AM   #3
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

Looks like a no-brainer to me. I can't imagine the fan ever runs anywhere near full speed, so I doubt the reduction in CFM would ever be noticed.


Herb

[EDIT: I also wonder if mounting the fan with some rubber washers might help isolate the vibrations from the fan to the fridge, and therefore the vibrations from the fridge to the fridge cabinet. IIRC, I think the noise from the fridge vibration was more noticeable than the fan itself.


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Old 03-30-2015, 09:25 AM   #4
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

86Scotty: Your fridge may have a different fan.........it would be interesting to know...next time you pull your fridge out for some reason of course....

I am a very light sleeper but the stock fan was nowhere near quiet.

Herb: The Samba threads indicate that some of the fridges came from the factory with 40CFM rated fans, so I'm assuming that it's whatever is available (within reasonable specs) when the fridges are built.
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Old 03-30-2015, 09:53 AM   #5
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

This is brilliant! I'm a super light sleeper, hence I always "had" to turn off the Norcold in my previous SMB so I could sleep (the noise itself I might have been able to tolerate, but between that and the fact that it is cyclical.... no way). That sort of worked out anyway as (at the time) it didn't have solar or any other means to charge the refrigerator overnight. Still, not ideal, as I woke up to 50 'fridge every morning.

Now I'm planning on putting in a Vitrifrigo (slightly larger one that the 49 though). Although I don't have it yet, I was already thinking about that darned (but necessary) fan! Definitely bookmarking this thread (and I'll report back which fan it does have, although I have to wait for the budget to plump up a little before buying the new fridge).

34 to 17 is a massive difference in db!

And obviously you could go back to the original fan if for some reason the cfm seemed too low. Actually, I don't exactly know what makes these turn on and off. Would a lower cfm fan run more often so that it would achieve the same results? I mean, does it "know"? Or will it run the same amount of time but just pumping fewer cfm (which may be fine anyway)?

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Old 03-30-2015, 01:25 PM   #6
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

Quote:
Originally Posted by Viva

34 to 17 is a massive difference in db!
Exactly......it's huge. The new fan is barely audible (the compressor is barely audible as well). There are probably cost constraints on the factory fans, the replacement I purchased was $17.


At a high level, as the CFM goes down the condenser temp will rise, leaving less deltaT for the coolant cycle. Since the thing cycles on and off, there is margin for cooling capacity, so I imagine that as long as it's cycling the deltaT is where it belongs.

The Samba thread has some very interesting observations done semi-scientifically (Measuring on-off times and interior temps) Another interesting point from the Samba thread is that the amp draw of the factory and replacement fans is considerably less than the specs once up and spinning.

I would expect that with a lower CFM fan, the max ambient temp where the duty cycle is 100% would be lower.

It appears that all three sizes of the Truckfridge use exactly the same compressors, evaporators, condensers, etc. I would assume that the larger units will have a higher duty cycle than the smaller ones, since TINSTAAFL.
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Old 03-30-2015, 05:25 PM   #7
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

I had to look that one up! I may have a pic or two of mine around. I'll look. Larrie had a thread on his fridge fan mod too, couple years back. You may be able to compare which fan he has as well since I remember some pretty up close pics.

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Old 03-30-2015, 10:23 PM   #8
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

I really question doing this. The fan is there to cool the condenser coil. The less air flow across the condenser the less efficient the condensation process and the more the compressor will run.

On the fridge that is my rig the compressor is actually noisier than the fan. Do it forget that the noise will be greatly reduced once the fridge is mounted in a cabinet. Good luck with the mod.
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Old 04-28-2015, 09:29 PM   #9
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Re: Making a Truckfridge Quieter (and isotherm and Vitrifrig

My Norcold DE441 came with a tiny computer fan mounted at the bottom of the unit, sorta aimed upward between the compressor and the coil. It was VERY noisy even installed in the box that SMB fitted it into.

I took that one off and used a 120mm computer fan from a Cooler Master case that is ultra quiet and moves more air than the tiny noisy one did. I mounted it on a slant, inside the coil so it sorta blows air at the compressor as well.
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