Laptop fan won't start - confirmed the fan is fine - what now?

[jeffreii]

So my backpack fell with the laptop in it but everything seemed to be ok...until it started turning off after 5-10 minutes of light use. I found it was because the CPU fan was not running. Rather than spend time testing (dumb), I just ordered a $10 replacement fan and installed it...still nothing.

My laptop has two fans so I was able to plug the new and old fan into the working fan port and confirm that all 3 fans that I have now are working fine...so the problem is not the fans.

I've inspected the motherboard and fan port and can find nothing wrong. It appears exactly the same as the working fan port - no damage or missing pieces.

What should I do/try/test now that I know it's not the fan itself?

Thank you in advance.

UPDATE: After testing I have found that on boot, the fan actually does turn on for 1-2 seconds, though it never reaches full speed (compared to the other fan) and then turns off and won't come back on.

 

[C12Friedman]

When the fan was replaced was the heatsink removed and if so was thermal compound cleaned off and replaced?

 

[jeffreii]

When the fan was replaced was the heatsink removed and if so was thermal compound cleaned off and replaced?

I did not have to mess with the heatsync. I would consider applying thermal paste anyways (as long as I took the whole thing apart I may as well!) but if the fan won't run, it doesn't matter I guess.

 

[DarkwingMkII]

It may be a wiring issue. Sometimes, the wires/cables can get damaged, fray over time, or even just get too dirty.
EDIT: It may also be the mount that the fan sits on is misshapen from the fall your laptop took.

 

[jeffreii]

It may be a wiring issue. Sometimes, the wires/cables can get damaged, fray over time, or even just get too dirty.
EDIT: It may also be the mount that the fan sits on is misshapen from the fall your laptop took.

The only wire is the one connecting the fan to the motherboard. Since all three fans work when connected to the GPU fan slot on the motherboard (each with their own wire), then I think I can rule out wiring issues.

The mount seems fine but I don't see how this would affect the fan turning on either way. I can plug the fan in to the GPU fan slot and leave it sitting on the table next to the laptop and it will run just fine - mount or no mount.

 

[jeffreii]

UPDATE: After testing I have found that on boot, the fan actually does turn on for 1-2 seconds, though it never reaches full speed (compared to the other fan) and then turns off and won't come back on.

 

[Paperdoc]

Your testing of the fan says that it works just fine when connected to the GPU fan port, but only runs for a couple seconds when attached to the CPU port. Was this testing done with the unit disassembled and open on your desktop?

The brief run you describe sounds exactly like the initial start-up of the CPU cooling fan. Its normal operation at start-up is to start at full speed for a moment until the BIOS has a chance to check the temperature signal coming out of the CPU. THEN the BIOS will slow the fan down to what is needed to keep the CPU temperature in control. Just after start-up, this often means the fan is NOT needed until the CPU warms up doing some work.

What I'm thinking is this: if you leave the CPU etc. exposed to room air currents with an open case, MAYBE the CPU does not heat up much, especially if you are not actually doing any work with the laptop. So the automatic CPU cooling controls in BIOS decide the fan is not needed, and leaves it off. The real test would be what that fan does when the whole thing is properly re-assembled so that that fan is the only source of CPU cooling and will be needed soon after start-up. Normal use would help to establish some work by the CPU and consequent heating, requiring fan use.

 

[jeffreii]

Your testing of the fan says that it works just fine when connected to the GPU fan port, but only runs for a couple seconds when attached to the CPU port. Was this testing done with the unit disassembled and open on your desktop?

The brief run you describe sounds exactly like the initial start-up of the CPU cooling fan. Its normal operation at start-up is to start at full speed for a moment until the BIOS has a chance to check the temperature signal coming out of the CPU. THEN the BIOS will slow the fan down to what is needed to keep the CPU temperature in control. Just after start-up, this often means the fan is NOT needed until the CPU warms up doing some work.

What I'm thinking is this: if you leave the CPU etc. exposed to room air currents with an open case, MAYBE the CPU does not heat up much, especially if you are not actually doing any work with the laptop. So the automatic CPU cooling controls in BIOS decide the fan is not needed, and leaves it off. The real test would be what that fan does when the whole thing is properly re-assembled so that that fan is the only source of CPU cooling and will be needed soon after start-up. Normal use would help to establish some work by the CPU and consequent heating, requiring fan use.

Thanks for your thoughts. I have tested it fairly extensively with both the new and old fans, both open and fully sealed/assembled. Either way the fan does not run, even up until the point right before the system shuts down after reaching nearly 100C CPU temps.

 

[Paperdoc]

Ouch! So it looks like your mobo's CPU_FAN port is not working. At least, it cannot do automatic control. You could try going into BIOS Setup to where that port is configured and setting it to a fixed speed setting (whether full speed or less) to see if the fan can run that way.

 

[jeffreii]

Ouch! So it looks like your mobo's CPU_FAN port is not working. At least, it cannot do automatic control. You could try going into BIOS Setup to where that port is configured and setting it to a fixed speed setting (whether full speed or less) to see if the fan can run that way.

I'm not sure if it has some sort of software error where the fan control is not working properly, or (more likely, I think) the fan port is shorting out as soon as it starts, causing it to immediately shut down.

Unfortunately, my BIOS has no fan control settings (!!) - it's an ASUS ROG G53SW-XA1. I even tried installing SpeedFan to take control of the fans but it appears Speedfan is unable to do anything. I believe the fan control is locked (or it would be accessible in the BIOS).

I think my options are: 1) new motherboard ($150) 2) try a cooling pad (not good for travel).

Hopefully someone else has some suggestions. Thanks again in advance!

 

[jeffreii]

Does anyone have any more ideas for me to try? Thanks!

 

[jeffreii]

It seems to me that the laptop cooling pads aren't going to be powerful enough to cool my CPU by themselves...does anyone have any experience regarding that? Thanks!

 

[tuckmert]

just want to say that i have the exact same problem with my brand new dell inspiron. The fan will turn on for a few seconds when booted up and will work when I run applications on my computer sometimes, such as steam games. However it ultimatley always overheats. Speedfan does not recognize any fan systems on my computer when i tried that.
Have searched for a month now on solutions, i'm thinking it might just be hardware issues. Besides this my laptop works fine. You are not alone.

 

[jeffreii]

just want to say that i have the exact same problem with my brand new dell inspiron. The fan will turn on for a few seconds when booted up and will work when I run applications on my computer sometimes, such as steam games. However it ultimatley always overheats. Speedfan does not recognize any fan systems on my computer when i tried that.
Have searched for a month now on solutions, i'm thinking it might just be hardware issues. Besides this my laptop works fine. You are not alone.

Thanks - my laptop has been a brick for months now...I'm almost ready to just throw it out but it's such a waste. I need to find a way to mod it somehow to power the fan but don't know where to start...

 

[tuckmert]

Have you tried to get it fixed by a professional, or under warranty?

 

[jeffreii]

Have you tried to get it fixed by a professional, or under warranty?

The warranty is long-expired and a professional probably is pretty pricey for a 4 year old laptop. I'm trying to find a good guide for how to mod the fan to run from one of the USB ports instead of the cpu_fan port.