I’m having a problem with my early 2008 iMac 2.8Ghz Core 2 Duo – Model Number A1225 /Machine number – MB325LL/A – RAM 6GB and and the original Hitachi 320GB internal hard drive. running 10.6.8
In order
( A) I noticed that the iMac’s internal hard drive was getting very hot and rising in temperature according to two applications I had previously installed , Macs Fan Control and smcFanControl were both showing that the internal HDD fan was not working ( 0 RPM ) and the fan’s RPM could not be adjusted .
( B) The other two fans were working correctly ( CPU and Optical drive ) and their RPM settings could be controlled by using either Macs Fan Control and smcFanControl
( C ) I then personally installed a new internal hard drive fan unit and at the same time cleaned out the other two fan units of a build up of dust .
( D) After reassembling the iMac I booted it up for the first time and once more the internal hard drive fan according to both applications Macs Fan Control and smcFanControl was not working and showing no RPM activity .
( E ) All so now the CPU fan unit was, going by the high noise I could now hear , rotating at a high RPM , but both Macs Fan Control and smcFanControl were now showing the CPU fan RPM to be normal ( 1200 RPM ) but clearly it was not .
I shut down the iMac and disassembled the front panel once more allowing me to visually see the hard drive fan unit , I then powered up the iMac and could see and feel that in fact the hard drive fan unit was working and blowing an air stream over the internal HDD .
I then re checked all the connections to make sure they were all properly in situ .
I then re assembled the iMac and re booted up , again once more the applications Macs Fan Control and smcFanControl showed that the internal hard drive fan unit was not working and showing again 0 RPM , when in fact I now knew that the fan was in fact working .
All so Macs Fan Control and smcFanControl both showed the CPU fan as working correctly at 1200 RPM , when in fact going by the high noise being produced , the fan was in fact running at a non normal high RPM , which could not be controlled by either Macs Fan Control or smcFanControl .
So currently this is the situation
1. The internal hard drive fan is physically working but according to Macs Fan Control and smcFanControl the fan is showing 0 RPM and its RPM cannot be controlled
2. The CPU fan is now running at high RPM , but Macs Fan Control and smcFanControl are showing the fan as working normally at 1200 RMP , but again with this fan unit the RPM cannot be adjusted by using Macs Fan Control and smcFanControl , and is stuck in a high RPM mode.
3. The CPU fan unit was working normally before I installed the new hard drive fan unit .
This has been a wonderful machine , and now I’m lost as what to try next .
Any ideas – Thanks