Diagnosing laptop fan failure
Laptops are usually keen on being as quiet as possible. So when the cooling fan on one of them dies, it's not as straightforward to diagnose as it would be with a desktop computer. Luckily, modern computers have a bunch of temperature sensors built in, so when it detects an overheating situation it will slow down the computer to prevent damage. But how do you get from "this computer is slow" to "I need to replace my fan"? Here's what happened to me:
The Symptom
Over the Memorial Day weekend I flew to New York with Sherry to visit my sister. I took my laptop with me, of course, and when I got to my sister's place I configured my laptop to access her wifi. While setting it up, I noticed that she used WEP encryption rather than WPA2 and I thought that was unusual since WEP is pretty old and not that secure anymore. As soon as I connected to the WiFi, my computer exhibited the symptoms of being dog slow. Mouse clicks would take seconds to respond, regardless of CPU usage. Applications would take forever to load. Because the act of me configuring the wifi and the symptom of a slow computer came close together, I assumed that they were related. What else could it be? That was the only thing that changed about my computer....
Down the Wrong Path
Well it was slow all weekend, and I chalked it up to her wifi somehow mucking up my computer. But when I got home, it was still slow. When I removed her WiFi configuration from my computer, it was still slow! Reboots didn't help, docking the laptop didn't help..nothing helped! At this point I decided to call it a night because I had work in the morning, I would tackle this problem again the next day.
Investigation
At this point, I started to broaden my scope: Maybe one the WiFi card got loose in all the travel. I checked it all out and it seemed OK, so what I decided to do was disable the wifi and see if that fixed things. There's a "airplane mode" switch on my laptop that shuts off any radio transmitters like WiFi and Bluetooth so I used that to shut them down, then I booted up my computer. SUCCESS! Fast computer! Back to normal! But I still needed to verify that the wifi was the culprit..I flipped the "airplane mode" switch again and turned the WiFi back on. Hmm..still fast! no issues..maybe it was a fluke? Wait -- well, no...it's slow again..doh...
I turned off the wifi again, and it remained slow. Which totally sucked because I had not figured it out yet. At least I could somewhat eliminate the wifi as the source of the problem. I started to broaden my horizon a little bit..what could make a computer run fast for a little bit, and then all of the sudden slow down?
Glimmer of Hope
It all clicked. I knew that computer's had over-temp protection that would kick in if the CPU got too hot. And I didn't really hear the laptop's fan at all. I put my hand next to the vent and didn't feel any air. That was a good indication, but I needed to be sure.
I decided to download a utility that gives you a bunch of readouts about the health of your computer called HWMonitor. It allows you to see things like voltages, temperatures, and fan speed of all the different parts of your system. Sure enough, I could see that my computer was signalling the fan to run at 100%, but it was spinning at 0 rpm. I decided a REALLY needed to be sure and I partially disassembled my laptop so I could see the fan with my own eyes, and turned the computer on. The fan was not moving at all. Even if I gave it a little push, it wouldn't spin.
In for Repair
Luckily, my laptop has a pretty comprehensive service manual available on the manufacturer's website, so I was able to follow easy instructions to take apart my laptop and access the fan. Unluckily, the steps to get the fan out involved removing EVERYTHING. I had to take apart the keyboard, display, speakers, unhook all the radio antennas, and remove the motherboard out of the case. Just to access the fan. You would think that since the fan is one of the few moving parts in a computer, it is then more likely to fail than other components, and thus it would be designed to be easier to replace. Not so.
Ordering a new fan was kind of tricky as well: It's not a standard off the shelf PC fan, but has a custom housing meant for this laptop. There are three different versions, all push the same amount of air, but they all use different amounts of amperage (and thus consume different amounts of electricity for the same performance). The one in my laptop uses the least amount of electricity; the most common one out for sale uses 3 times the amount of electricity to push the same amount of air!
Anyways my laptop is now in pieces. I have the dead fan in my grubby hands and a new fan on order.
