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CSCustomCars
Explorer
May 10, 2018

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

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?
  • 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.
  • 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

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