12 Volt Computer Fans not working (long-ish post) SOLVED

[CSCustomCars]

Hello everyone,
I'm trying to install some computer case fans in my roof vent that has no fan in it above the kitchen stove (who's idea was that?).
The problem I'm having is they will not work when connected to power in my trailer.
Let me add, I am an auto mechanic, have the knowledge and skill to diag for the most part, but am at a loss here because it doesn't make any sense.

I bought two of these fans:
THERMALTAKE RIING 12 SERIES
Specs:

P/N CL-F038-PL12BU-A
Fan Dimension 120 x 120 x 25 mm
Started Voltage 9.0 V
Rated Voltage 12.0 V
Rated Current 0.2 A
Power Input 2.4 W
Fan Speed 1500 R.P.M
1000 R.P.M (with LNC)
Max. Air Pressure 2.01 mm-H2O
Max. Air Flow 40.6 CFM
Noise 24.6 dB-A
18.7 dB-A (with LNC)
Bearing Type Hydraulic Bearing
Life Expectation 40,000 hrs,25?
Connector 3 PIN + LNC (Low-Noise Cable)
Weight 158.8 g

Yes, this is a 3 pin fan, however, the third wire is just a hall effect sensor to tell the CPU how fast it is spinning.

With each fan mounted, I tested each with a 9v battery. Both started working. I then wired a cheap switch to both fans on the ground side, connected both fans together, wired the ground through the switch, then connected again to a 9v battery, flipped the switch fans turn on, flip the switch fans turn off.

I tap into power at the bathroom fan. I get power from before the bathroom fan, and ground after the switch for the fan. Connect up the fans in the kitchen, and nothing. I reconnect to a light on the ceiling, nothing. Disconnect, check again with a 9v battery, still works with a 9v. Bathroom fan still works fine.

What on earth is going on here? Do I need a voltage regulator before the CPU fans? MOST CPU fans will operate over 12v, even up to 20 volts. They have very little draw, only .4 amps. The fuse for the bathroom fan is 7.5 amps.

I checked on the manufacturer's website for impedance protection and I didn't find any info about them being protected.

My last idea to hook up direct to the battery (fused) to see if it's something about the wiring they don't like.

My trailer is a 2019 Gulfstream innsbruck 199RK. The lights are LED, but the bathroom fan is labeled as 12 volts. Is it possible when plugged into shore power that it runs off AC?

I haven't found my multimeter yet, but it's in here somewhere. I don't see how I don't have power at these fans when hooked up to a power source that is 12 volts and they won't work.

Does anyone have any ideas?

[landyacht318]

Your fans would exhaust more air if they were in a shroud which would not allow some portion of the air moved, to do a quick U turn and go through the fan again.

I've emplyed a 160CFM 230MM 12v computer fan as a stick and brick bathroom fan that could not use the traditional bathroom fans. Mounted in a acrylic tight fitting shroud in an upper window exhausting. Close the door and place a round pencil in front of it the 1/2 gap under the door, and it rolls across the room from the air flow from the fan on the other side of the bathroom. Without a shroud, fan just leaned against the screen, the pencil stays put with little discernable airflow coming under the door.

120Mm fans are numerous. I like the Silverstone fm181, 180Mm fan, as it comes with a potentiometer for speed control. At full speed it draws 0.28 amps and moves 160CFM and is still quiet. At lowest speed it is ~60CFM and practically silent, and 0.09 amps

Noctua makes extremely well designed computer fans.

The 200 MM NF A20 consumes 0.08 amps at 12vDC, and moves 86CFM for 18DB

More airflow than your 2 fans for 1/5 the electrical comsumption and likely half the noise, or less.

NOctua also has industrial fans, and some of these are IP 67( others are IP52) ratings, which should be better for cooking under. I have cooked under a silverstone fm121 for going on 8 years so apparently the grease and cooking fumes are not really a worry.

Noctua has their own PWM speed controller that can control multiple fans' speed

The 3000 rpm Industrial Noctua NF-f12 9120mm) draws only 0.3 amps and moves 110CFM and has a very high static pressure rating, and can easily be tamed to tolerable noise levels with their speed controller.

I employ two of them as intake fans, along with the silverstone fm181. Al three of them on max speed draw less than an amp and if they had no airflow restrictions in front of or behind the impeller, would move nearly 385CFM.

[MrWizard]

never mind

glad you solved it

[CSCustomCars]

MEXICOWANDERER wrote:
Try reversing the polarity 🙂

I both love you and hate you 😉

Switched the wires, works fine.

Thanks everybody for your help.

[CSCustomCars]

Took some pictures to clerify.

These are the fans, mounted wired.



Here are thw two wires coming from the bathroom fan, and then my meter connected to the two showing the voltage.

[CSCustomCars]

MEXICOWANDERER wrote:
Try reversing the polarity 🙂

If that fixes it I'm gonna scream.

Trying it shortly, uploading some pictures of what I'm on about.

[MEXICOWANDERER]

Try reversing the polarity 🙂

[CSCustomCars]

wnjj wrote:

CSCustomCars wrote:
Found my meter, and confirmed I have 13.7 volts coming from the bathroom fan to the computer fans. This is with the bathroom fan off as I want to run the computer fans independently from the bathroom fan

Did you use the meter directly across the 2 wires heading to your new fans or use a ground from somewhere else? Any chance you have 2 hot wires connected or are actually connected to a switched ground?

Connected directly to the two wires going to the new fans from the bathroom fan.

[wnjj]

CSCustomCars wrote:
Found my meter, and confirmed I have 13.7 volts coming from the bathroom fan to the computer fans. This is with the bathroom fan off as I want to run the computer fans independently from the bathroom fan

Did you use the meter directly across the 2 wires heading to your new fans or use a ground from somewhere else? Any chance you have 2 hot wires connected or are actually connected to a switched ground?

[CSCustomCars]

grizzzman wrote:
Have you tried the LNC cable?

No because it's only for reducing electrical noise from the fan to the CPU when used for it's intended purpose. LNC is Low Noise Cable.

[grizzzman]

Have you tried the LNC cable?

[CSCustomCars]

Traver8 wrote:
It is not exactly clear from your description of getting power and ground from the bathroom fan but it seems to me that you may be getting both constant 12 v from before the switch and switched 12 v after the switch and not ground. Take another look at the bathroom fan connections and be sure that you are really getting 12 v and ground.

If I misunderstood your description, sorry but that is my first impression.

Let us know more of your checks as things progress and we will try to help.

Terry

Found my meter, and confirmed I have 13.7 volts coming from the bathroom fan to the computer fans. This is with the bathroom fan off as I want to run the computer fans independently from the bathroom fan

I'm not sure what you mean by your first paragraph. There is a second switch after tapping power from before the bathroom fan on the ground side to the computer fans, thus negating being in a constant 12 volt state. I tested this wiring directly with a 9 volt battery and confirmed both the fans and the switch is wired correctly, and working.

Basically what's going on here is a 12 volt fan will work when connected to 9 volts, but not when connected to the trailer with confirmed 13.7 volts coming in.

EDIT: Oh what you're saying is (correct me if I'm wrong) that my ground switch on the computer fans will only ground if the bathroom fan is on. If that's what you mean, then I already I tested that as well. I turned on the bathroom fan after connecting everything to insure it worked. I also tried turning on my computer fans with the bathroom fan running and I still have nothing.

[Traver8]

It is not exactly clear from your description of getting power and ground from the bathroom fan but it seems to me that you may be getting both constant 12 v from before the switch and switched 12 v after the switch and not ground. Take another look at the bathroom fan connections and be sure that you are really getting 12 v and ground.

If I misunderstood your description, sorry but that is my first impression.

Let us know more of your checks as things progress and we will try to help.

Terry