120mm pc fan to ac/dc, running slow

So I have a 120mm pc fan with the following specs:

Voltage(V): 12
Current(A): 0.32
Power(W): 3.84

hooked up to a AC/DC converter with 12V, .500 A, and I'm getting very low RPMs from the fan. For some reason it's not getting enough juice, or maybe it's something else. Tried two different adapters.

FWIW there are 3 transparent wires attached to the fan as opposed to the classic red/black/yellow. Two of the wires are connected to the converter (which I believe are red and black since it was the only combo that worked)

Any help is appreciated!

I think you might have a low CFM fan. Sounds like the fan is designed to run quietly so it won't go as hard as a normal fan.

From what he states it seems that he is aware of the fans normal operating RPM and with his AC/DC converter he is seeing it running at much lower rpms.

I've never used any form of converter other than a phone charger and i just selotaped it all together and my fans gave me their expected flow rate and rpm etc. The third wire is a speed control wire so you can ignore that really, that's for the copmuter software to play with, without that it should just run at full power if it is reeiving the correct power.

Not much i can suggest other than trying to wire it up to an alternative power suply and seeing if there is a difference.

dimebong said:

I think you might have a low CFM fan. Sounds like the fan is designed to run quietly so it won't go as hard as a normal fan.

Click to expand...

sorry, forgot to mention that it's supposed to run at 103 CFM @ 2000RPM. defective unit perhaps? how to test?

@ tip top: it's an adapter, not a converter. fail on my part. looks something like this

Low CFM cheap chinese junk. I bought 4 last summer. Only one works correctly 2 are slow and one does not work at all. If you ant a PC fan that really works you need something like Thermaltake Not cheap not quiet. $10 was cheap sleezebay cost
Thermaltake A2218 UFO Blue UV Twin Blade 90mm Fan with 80mm Fan Adapter variable speed 26 to 81 CFM



Use pc power supply not an adaper

If you're sure it's a 12v output it would most likely be the adapter not putting out enough
power. If you don't have a voltmeter then you should take a fan out of your computer,
shove some pins into the female plug of the fan and see if it runs normally.

Lmfao! That's one of the first times in a long time i've heard someone try and claim thermaltake make quality products

so I've been reading and it appears that pc case fans require dc power. now mind you I'm a complete noob when it comes to this stuff, but is there any chance my ac-dc adapter is somehow incompatible with the fan? In other words, do I need a dc (only) adapter instead of ac-dc or does it not make a difference?

If it plugs straight into the wall, it is by it's very purpose an AC to DC adaptor. There's no other way aorund it. The only way for it to be DC-DC is to start off with a DC current, which a wall plug is not.

As i said, i have used phone chargers with my fans and they work just dandy. If your fan is ot getting upto it's appropriate RPMs, then there is a fault with your adaptor or the compatability between the adapter and the fan.

Find an old phpone charger or a friend who has one, and see what if any difference there is. I used the first charger i came across in my box of odities, and it was only good for 7v, and the fan worked exactly as it always did when run on 7v (i always contorl my fans via voltage with my computers)

all my old chargers are 5V which isn't enough to give me decent airflow... I really don't want to buy a power supply to run a single fan. what can I do???

I run my pc 12V fans with a 12V auto batery charger. That adapter you're using may not put out enough for your fan. either that or as said that may be the fans full output but I doubt it. I also have a DC power supply that I can adjust and can run my fans on 15VDC.

PurpleDays said:

So I have a 120mm pc fan with the following specs:

Voltage(V): 12
Current(A): 0.32
Power(W): 3.84

hooked up to a AC/DC converter with 12V, .500 A, and I'm getting very low RPMs from the fan. For some reason it's not getting enough juice, or maybe it's something else. Tried two different adapters.

FWIW there are 3 transparent wires attached to the fan as opposed to the classic red/black/yellow. Two of the wires are connected to the converter (which I believe are red and black since it was the only combo that worked)

Any help is appreciated!

Click to expand...

Are you sure what you're reading on the power supply is not 500ma? that would be 500 milliamps, and not close to the .32 amp load created by the fan.
Also you should use a power supply, not just a charger....... I don't see in your notes which one you have.

I wonder if the 3rd wire is a speed controller,but that should not effect a direct neg pos hook up.Does your fan have a thermistor?
It should be a blue two lead cap capacitor looking thing mounted on the fan housing.

.500 ma should be enough for required .32,but your charger transformer housing does not look beefy enough for .500 ma but I could be wrong.

the exact model of the adapter

also, I hooked the fan up to my pc and it gave me the same RPM as with the adapter. what is going on? is it maybe set to run at low RPM by default? I thought speed was determined by voltage (the adapter itself allows you to change volts, 3-12, and was giving me low RPM at 12v). anyway I'm super confused now.

tip top toker said:

Lmfao! That's one of the first times in a long time i've heard someone try and claim thermaltake make quality products

Click to expand...

I did not, would not call it quality
I only said they work.
Its just a notch above cheaper chinese junk
Cheaper chinese junk are generally less than $2 including shipping from Hong Kong.

Fry's has a good selection of replacement fans from $5 to $200 for fancy stuff.

it might be the fans thats having the issue if you say that you have that adapter fromthe link.

adapter from the link has 1A
your fan has .32

1000 - 320 = 680ma remaining power..

this should easily run 2 (3 if you really want to load it) fans safely. with some left overs.

look into getting new pc fans -- or try some old fans you have laying around and see if the adapter is the issue.

goodluck!

----

im running 6 fans with 1 adapter right now.

get this......
http://www.ebay.com/itm/120728532313?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
And these......
http://www.ebay.com/itm/251138377794?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
forget the variable speed adaptor,,,variable speed fans are what you want!!!! I have my 2 exhaust fans running thru the cctv power supply, and my intake running thru a variable speed adaptor that never leaves the 12v setting(expensive mistake). Why try to run a 12v fan on anything other than a 12v power supply???? Ma is a non-issue with 12v 2amp.