Need help on Molex Y Splitters

MadSupra354 · 27 Jan 2012

I bought a sound card recently that required a Molex connection for power. When I built my computer, I only had enough connectors for the fans, and left out the case LEDs. So I had to disconnect a case fan for the sound card, in this case, the fan at the top above the CPU cooler to push air outside. There is the fan at the left (Back) of the case, but I didn't want to risk leaving only that fan exhausting air.
Here's what you need to know: PSU Molex connector is female, and the sound card and case fan is male. I think the other one is the case LEDs, which is female.
I bought a Male to 2 Female Y Splitter, connected the card to the PSU Molex connector and the fan. But the fan is pulling air in rather than pushing out. So what have I done wrong?

kodi · 27 Jan 2012

It's not the wiring, the fan needs to be taken out and turned around.

alphanumeric · 27 Jan 2012

It shouldn't be possible as the connectors are keyed, but it sounds like you have something plugged in back wards so that the polarity is reversed. Are you sure the fan isn't just in back wards. There should be arrows on the fan body showing fan rotation and airflow direction. Compare that to how the is actually working. If they match up then just reverse the fan in the case. If the fan is actually turning the wrong way double check your wiring. On the molex connector Yellow is +12V Black is ground and Red is +5V. On the fan usually red is + and black is - or ground. The third wire if there is one is the fan speed sensor. If your fan has the 3 pin to 4 pin molex adapter cable my bet its flipped where the two small 3 pin plugs connect together.

MadSupra354 · 27 Jan 2012

I'm pretty sure the fan is actually spinning the wrong way. It was pushing out beforehand.
They both have 1 red, 1 yellow and 2 black, and they're 4-pin. You're saying I should switch them around?

ignatzatsonic · 27 Jan 2012

Does your visual observation of the air flow direction contradict the air flow direction arrow that is typically stamped on all fans?

alphanumeric · 27 Jan 2012

If its plugged in correctly the colors should match up, yellow to yellow and red to red. Check the arrows on the fan to see if it is spinning the wrong way.

EDIT: Even if you revered one of the plugs it would just turn slower not back wards, it would get +5V instead of +12v. I'd say you'll have to flip the fan around in the case to get the airflow you want.

MadSupra354 · 27 Jan 2012

I didn't see any arrows, but hopefully pictures help.

Need help on Molex Y Splitters-sany0011.jpg

ignatzatsonic · 27 Jan 2012

Can't see enough in that pic. The arrows can be hard to see. Look around the narrow edges of the fan. It will just be a simple arrow like =>.

bobkn · 27 Jan 2012

Brushless DC motors (most fans these days) don't run backwards if the input electrical polarity is reversed. They don't run at all.

tw33k · 27 Jan 2012

The fan looks to be positioned to push air out of the case but you're saying it's pulling air in? You need to respond to alpha's post about the color of wires matching up. Do they?