iMac fan issues

cheeseandbeans

macrumors newbie
Original poster
Feb 19, 2014
2
0
Greater Manchester
Good Evening!

OK I purchased a mid 2011, 21.5, i5, 2.5ghz iMac from ebay the other day that was listed as slightly faulty. As I was looking to buy my first iMac and I had a tight budget I thought I'd give it a go. I work with computers and thought I could have a go at fixing the issues.

So this brings me to the problem, the seller said it was bought as part of an office clearance so not much history behind it and that when it was on one of the fans was noisy.

It's arrived today and true to form one of the fans is noisy. I've spent the past couple of hours researching the issue on the internet. First thing I did was run the online AHT. This brought back an error code of 4MOT/4/40000002:CPU-0. I think this refers to a faulty cpu fan but the noisy fan is coming from the right hand side of the screen?

I then downloaded smcfancontrol. Currently the ODD fan is running at 4300rpm and 46 degrees (I presume this is the noisy fan I hear). The HDD 1099rpm and 46 degrees and the CPU fan 0rpm and 46 degrees?

So I suppose my question is, where do I start to fix this? Why would a faulty cpu fan make the odd fan run at max?

Thanks in advance
 

RemarkabLee

macrumors 6502a
Nov 14, 2007
557
3
Good Evening!

OK I purchased a mid 2011, 21.5, i5, 2.5ghz iMac from ebay the other day that was listed as slightly faulty. As I was looking to buy my first iMac and I had a tight budget I thought I'd give it a go. I work with computers and thought I could have a go at fixing the issues.

So this brings me to the problem, the seller said it was bought as part of an office clearance so not much history behind it and that when it was on one of the fans was noisy.

It's arrived today and true to form one of the fans is noisy. I've spent the past couple of hours researching the issue on the internet. First thing I did was run the online AHT. This brought back an error code of 4MOT/4/40000002:CPU-0. I think this refers to a faulty cpu fan but the noisy fan is coming from the right hand side of the screen?

I then downloaded smcfancontrol. Currently the ODD fan is running at 4300rpm and 46 degrees (I presume this is the noisy fan I hear). The HDD 1099rpm and 46 degrees and the CPU fan 0rpm and 46 degrees?

So I suppose my question is, where do I start to fix this? Why would a faulty cpu fan make the odd fan run at max?

Thanks in advance
I would imagine the CPU fan is faulty. The ODD may be running up to max to compensate. Either the CPU fan is faulty, or the connectivity to the mainboard is broken. Check ifixit.com.
 

RemarkabLee

macrumors 6502a
Nov 14, 2007
557
3
The OP said the CPU fan was at 0 RPM, which to me reads like a issue related to that as primary culprit.

I would investigate both CPU and ODD fans/sensors anyway to be on the safe side :)
 

cheeseandbeans

macrumors newbie
Original poster
Feb 19, 2014
2
0
Greater Manchester
Further info

Tried a New cpu fan and it hasn't resolved the issue. On closer inspection there is a scorch mark next to the fan connector. I think one of the resistors has blown but I don't know if they can be replaced?

See below links to 3 pictures I have taken. I think the missing component says L5720. Would be good if someone could upload a picture of that area on a working logic board.

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