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Intel Mac Mini + Water = Loud Fan!

B

bitty417

macrumors member
Original poster
Jul 2, 2007
86
0
So here is the unfortunate series of events:

My C2D Mini is on my desk, along side a freshly topped off glass of water. Cat jumps on the desk and water is everywhere. When as I was reaching to lift the mini I heard the fan throttle up to full speed and then the display turned off.

I immediately unplugged the mini, toweled off the bottom and opened the case up. From what I could see there were only a couple of drops of water on the bottom portion of the case towards the front. I dried off the inside and waited about 1 hour. When I first plugged it into power the fan went up to full speed without me pressing the power button. It would not boot. I again let the computer sit for one hour. This time the machine booted fine but the fan was at full throttle.

After some digging around online I read that resetting the PMU sometimes helped (http://docs.info.apple.com/article.html?artnum=300574). I later read down the article and realized that this procedure is not meant for the Intel minis! :eek: After some more digging around I found that this procedure can sometimes cause the behavior I was looking to get rid of!! :mad: (http://discussions.apple.com/thread.jspa?threadID=1476991&tstart=30)

I finally found the proper procedure, resetting the SMC (http://docs.info.apple.com/article.html?artnum=303446) and did this along with a reset of the NVRAM (command-option-P-R during startup). Initially it appeared to have solved my problems! The machine started up as normal with fans hovering around 2500-3500rpm depending on load and stayed normal for about 30 minutes before creeping up to 5500rpm and staying there since. :(

Repeating this procedure yields the same results -- fan works normally for a brief period then goes up to full speed.

I have since opened the case up to check all connections and just generally look around. I can't see anything worth mentioning. Every connection has been closely checked. The machine is running normally except for fans constantly at 5500rpm.

I've noticed the ambient temperature sensor is reading ~250F. I can't find the location of this sensor. I'm using iStat Pro to measure fan speed and temps. I figured I would just blow air in the front of the case to see if I could affect this sensor. Sure enough once I started blowing into the front the reading dropped to -85F. If I continue doing this the reading stays steady at -85F and the fan starts to slow down. Once I stop the temperature goes back up to ~250F and the fan throttles back up to 5500rpm.

Now what the hell do I do?? I'm glad that the machine is working all things considered. I think I've come pretty far trying to figure out what is going on but now I'm at a dead end. The fan noise is driving me nuts! I miss my quiet little mini. How do I fix this? Did I cause this by first trying to reset the PMU?

It's been a rough weekend ... :(:(:(
 
Hmm.

I really am not sure how you might fix this. Although to me it seems that your sensor has been damaged/had its settings changed in some way. I would suggest trying to figure out a fix for that, and if all else fails, bringing it in to the Apple store.
 
rolex54 said:
if you could locate the temperature sensor i wonder what just cutting it off would do
that could solve it if you were able to find it

EDIT: I did some searching and found this it may be a very helpful thread for you
http://www.123macmini.com/forums/viewtopic.php?t=18111&sid=c8e119a9532e843346186630885afc04
Click to expand...

Sounds interesting but I checked this cable EXTREMELY closely and there is no cut or break in the cable. It is definitely seated properly. Furthermore, this sensor and cable appear to be a hard drive temp sensor (http://www.welovemacs.com/9227319.html). The HD sensor is reading ~86F right now.

Anyone know where the ambient temp sensor is located? This is the one reading ~250F.
 
seem like strange suggestions

What kind of suggestion is that, 'cutting of the temperature sensor'?
If's like removing the fire alarm in a burning building to get rid of the problem... :eek:

The sensor is clearly indicating the temperature of some component is TOO HIGH. You did the test by blowing in air which made the temperature drop. This means the sensor works fine and the fan works fine, there just seems to be a component that must have had a short circuit which turns hot. The sensor picks up the high temperature and brings on the fan to cool it down, just as it is supposed to. So the problem is the overheating component, nothing else. The resetting doesn't solve anything, it just makes the sensor 'forget' it detected a hot component. :cool:

If you can't locate the 'hot' component, I suggest you take it to the Apple Store. :eek:
 
zjokke said:
What kind of suggestion is that, 'cutting of the temperature sensor'?
If's like removing the fire alarm in a burning building to get rid of the problem... :eek:

The sensor is clearly indicating the temperature of some component is TOO HIGH. You did the test by blowing in air which made the temperature drop. This means the sensor works fine and the fan works fine, there just seems to be a component that must have had a short circuit which turns hot. The sensor picks up the high temperature and brings on the fan to cool it down, just as it is supposed to. So the problem is the overheating component, nothing else. The resetting doesn't solve anything, it just makes the sensor 'forget' it detected a hot component. :cool:

If you can't locate the 'hot' component, I suggest you take it to the Apple Store. :eek:
Click to expand...

I don't think a component is overheating inside the machine. All of the other temps - CPU/HD and Chipset, appear normal. The machine runs perfect and there isn't a ton of heat coming off of it. Also, I doubt me blowing on a sensor which was reading 250F would drop it down to -85F in a few seconds. That right there tells me the sensor is faulty.
 
The ambient temp sensor is a tiny thermistor hidden in the midframe assembly. Its between the HD and optical drive, you need to pull the frame and then pull the HD to see it. It connects to the logic board at the front in the middle via a two pin connector. If you disconnect it, it will have the same effect on the fan. The Apple part number is 922-7319 if you can find an AASP who will sell you one.

War
 
Waragainstsleep said:
The ambient temp sensor is a tiny thermistor hidden in the midframe assembly. Its between the HD and optical drive, you need to pull the frame and then pull the HD to see it. It connects to the logic board at the front in the middle via a two pin connector. If you disconnect it, it will have the same effect on the fan. The Apple part number is 922-7319 if you can find an AASP who will sell you one.

War
Click to expand...

Thanks so much for the info. I'm showing this part as a HD temp sensor though -- is this just a mistake? http://www.welovemacs.com/9227319.html
 
bitty417 said:
Thanks so much for the info. I'm showing this part as a HD temp sensor though -- is this just a mistake? http://www.welovemacs.com/9227319.html
Click to expand...

Good question, obviously I am using different software to read the sensors, so it may simply be the label which is different. What other sensors do you have listed?

The HD (SMART) should have a built in sensor. Then the CPU and maybe the GPU will have them too. Not too sure what else off the top of my head. I will see what temperature monitor and menu meters report on this mini. Perhaps you could run your Apple Hardware Test.
 
Actually you could also try disconnecting the ambient sensor. As I say its right on the front edge of the board. You only have to take the lid off in order to disconnect it. Then see if its still reporting 250.....
 
Waragainstsleep said:
Good question, obviously I am using different software to read the sensors, so it may simply be the label which is different. What other sensors do you have listed?

The HD (SMART) should have a built in sensor. Then the CPU and maybe the GPU will have them too. Not too sure what else off the top of my head. I will see what temperature monitor and menu meters report on this mini. Perhaps you could run your Apple Hardware Test.
Click to expand...

I'm using iStat Pro to measure temps and I have noticed that occasionally sensor names will change. I have CPU A, B, Ambient, HD and Northbridge. How do you run the Apple hardware test?
 
Waragainstsleep said:
Actually you could also try disconnecting the ambient sensor. As I say its right on the front edge of the board. You only have to take the lid off in order to disconnect it. Then see if its still reporting 250.....
Click to expand...

I'll try this tonight and get back to you. Thanks for all the help!
 
An idea - probably disconnected the sensor cable

Hey

I have a feeling that you may have accidently disconnected the sensor cable. When you took the cover off at the very front there is a small connector cable and you may have accidently disconnected it. Generally your fan speed should be around 1500 rpm. 5500 is max speed.

go to the link below to see the cable that I am talking about. I highly doubt that the water had anything to do with your machines fan speed. Especially only a few drops of water. The 5th photo is the cable I am speaking about, this controls your fan speed, when disconnected or if the wire are cut then the fan speed is 5500 rpm.

http://www.applefritter.com/Mac_Mini_Take_Apart_Guide


Good luck, let me know.

Upsidedownguy :)
 
Did you fix the loud fan?

Hi,

I have someone who has (not a cat!) also spilt water on their mini resulting in a loud fan.

just wondered if you found a fix.

Thanks
 
Solved

Just so people know, my issue is different but I bought a used intel core solo mini on Craigslist and I powered it up and it had a loud fan. Took the cover off and the temp sensor on the front was unplugged. Plugged it in an problem solved.
 
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