Isotherm Fridge fan failing

[Frosty]

I assume you crimped couple of flat terminals in place of the PC motherboard fan connector? And just forget about any signal / tacho “3rd” wire?

All the best / M

Oh, yeah -- that was a minor pain. So there are 4 wires on the fan. We only use two, which are the black (negative) and the yellow (positive). They all end in a tiny connector that doesn't do us much good.

So, Noctua supplies an "extension" cable that connects to the stock fan connector. What I did was use that as my modifier, thus allowing me to work away from the fan, plus retain the quick connect ability.

I ended up with two extension cables (because I bought an NFF before Noctua got back to me explaining that the NFA would be better for my application), so I tried two different ways.

Way one was I soldered the tiny (tiny!) Noctua extension wires to my own 18AWG extensions. Way two was I used pink butts to join them but I put both wires into one side of the butt before crimping and simply crimped the other end closed, then activated the butt's heat shrink. In both cases I also put a length of separate heat shrink over the whole joint, mostly for strain relief.

In both cases I then crimped the standard quick connect blades onto the other end of my 18AWG pigtails, which go on terminals positive and F on a Danfoss Secop BD 35 (I think BD 50 is same).

I also used more standard colors for my extension wires so it is "normal" on the quick connect compressor end (yellow being positive ....no thanks). In the end I think I feel a bit better about the one I dead-end crimped into a pink (18-22AWG) butt, however both ways worked.

I cut off the two unused fan wires on the extension and sealed the ends.

You could do either of these ways right onto the fan wires thus skipping the extension and their connector. Mine in this case was in a dry environment (non-boat) so I kept it.

 

[rhapsody34]

Thanks Frosty for this thorough writeup.

I will totally go for an NFF type as I have the “free air” condition around my BD35 compressor. The soldering and heatshrink solution seems like the best one for me, and why not make use of the extension cable to make for easier connectivity. The fan appears to have a 0.05 A nominal current draw which causes negligible voltage drop anyway.

I have a way forward now.

Big kudos!

 

[Comodave]

I put one of these in the cabinet of our refer about a couple of years ago. It blows into the cabinet by the compressor and there is a vent in the top of the cabinet that I added. Refer works way better now. It is a 50 mAmp fan. Got it on Amazon. Hardest part was the tiny wires going to the fan were tough to splice onto.

Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown)

 

[Frosty]

I think that's the same fan we've been discussing. Maybe it sounds funny to be so excited about a fan, but I was blown away (ha) by how much nicer it was than the stock one (Costech) on my BD35. The Costech was flimsy feeling and loud. The Noctua heaver, better type of bearing, lots of rubber to dampen sound, and so much quieter.

The one you mention (the NF-F) is best for when you are blowing air around in a "free" condition (such as in a cabinet). The NF-A that I ended up with has more static pressure, so it's better for sucking through a "solid" radiator type thing (forget the correct term for that part at the moment, sorry), which is the situation on my BD35 (but there are BD 35's set up in various ways so some have the free-air situation).

While we are on the topic, it is also possible to set up a second fan on the electronic control box that will also come on when the compressor comes on (maybe that's what you did to get more air flowing through your cabinet).

You can also hook an LED light across terminals D and + and that will display fault codes (blinks). I think that's already set up on some refrigerators.

You can also put in different resistors (than the stock one) to have the compressor run at various different RPM's (this is sanctioned as ok). They pick a middle of the road one typically because people don't want to hear the compressor run a lot (even if it may be more efficient). Also, the higher the RPM the quicker the cool down if you use the unit in a way where that is a good feature (lower RPM typically uses less electricity). That's across terminals T and P as I remember it.

Okay, tangent city, but I like how you can tweak it a bit if you want to.

 

[Comodave]

On my refer there is a terminal “F” that supplies up to 500 mAmps for a fan that comes on only when the compressor is running. That is where I took power off of. But at 50 mAmps it doesn’t really matter if it were to run more. My freezer now keeps ice cream hard and it never did before.

 

[Frosty]

On my refer there is a terminal “F” that supplies up to 500 mAmps for a fan that comes on only when the compressor is running.

That's the one. On my BD35 the stock fan is also on "F" and + (it comes as part of the compressor unit). But as you say you can add an additional one as long as the total load is under the limit. These fans draw so little --- it's amazing to me.

 

[Comodave]

So far I don’t see the need for a second fan but I could actually add 9 more and still be within the limit...

 

[rhapsody34]

Interesting about adding a fan for extra circulation in the cabinet. My “cabinet” where the compressor is installed is part of the rear big stowaways in the boat which makes for OK air ambience unless the weather is really hot.

Mine has the ASU electronics unit placed onto the stock black control unit, which means there’s only one set of fan output terminals apart from the 12V input terminals. However with a 0.05 A draw per fan, I see absolutely no issue in soldering up a parallel wire kit for two NFF fans, one for BD35 and one for cabinet. It would only do good for the ventilation of the boat. I’ll go ahead and order 2 x NFF’s

 

[rhapsody34]

...or perhaps an NFA for the cabinet vent.

 

[Frosty]

I see absolutely no issue in soldering up a parallel wire kit for two NFF fans, one for BD35 and one for cabinet. It would only do good for the ventilation of the boat. I’ll go ahead and order 2 x NFF’s

Sounds like a plan. Another possibility is to use a pair of the blade piggybacks.

The NFA is better for higher static pressure. Like say it was right behind the radiator in your car, trying to suck air through the radiator. The NFF is better for "free" air, such as in a cabinet. (Even a small, cramped cabinet -- as long as the blades are not literally trying to suck through a blockage as in the car radiator example.)

 

[Dougcole]

As the Oh Pee on this thread I have been enjoying watching it evolve. For the record, since I replaced the controller I haven’t had any more fan failures. Overall I love my isotherm box.

Interestingly, the only issue I’m currently having is that it does not work on AC power. It works fine on DC, so it’s not a big deal, but do y’all have any thoughts on that? I’ve verified that there is AC power coming to the unit.

 

[rhapsody34]

Hi Dougcole, thanks for letting us hijack this thread quite a lot


For the AC side of things, I'm sure your unit has a separate transformer + rectifier or a switch-mode converter. I had a transformer in my previous unit, a "portable" dual-power Indel TB31 box that housed an Isotherm compressor unit. I remember it as being 100% stable on 12 V but a bit dodgy and not always cooperative on AC power



You might have a fuse issue or something "worse" that needs replacement in your converter. For what it's worth and if physical fit is not super important, the AC to 12 V job can be quite easily replaced if you like DIY and know what you are doing. For example, old retired desktop PC PSU parts are a good (free) source of safe 12 V power from a grounded AC source.