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Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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HELP My 2008 iMac CPU Fan runs at full speed.

My 2008 iMac CPU fan runs at full speed. I tried to control the speed via Mac Fan Control app but no luck, I can control the other fans perfectly.

Short context:

The iMac belonged to my father, he had it in his company, I was a little young, I remember that they had to take the Mac to technical service because it was getting hot and since they repaired it and returned it to my father the fans were always going fast.

Now that I am older, 2 years ago I decided to replace the GPU to bring back to life the iMac because the screen had so many lines. While I assembly the iMac I remember and noticed a connection between two solder points on the CPU fan connector.

I have a suspicion that this is the reason why the CPU fan is running like this, I don't have a picture but I will leave an image recreating what I saw when I put the iMac together, it would be helpful if someone can confirm if this is the case.

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@pipe119 "they had to take the Mac to technical service because it was getting hot " and it looks like the fix was to bridge the fan power line (motor controller) with the fan tach line. Hence you always get full speed on the fan. If you remove the solder bridge, you most likely will have the old error back. You can try and control the speed via Mac Fan Control app with the solder bridge removed. It may or may not work, if the original issue is on your fan tach line

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I just disassembly the Mac now, I’m a noob in this situation because I never do this type of things, I would appreciate it if you could tell me how I can remove the solder without damaging anything.

To avoid overheating I will use Mac Fan Control so I have no problem, previously had that problem as they did graphic design on the iMac every day until 2015.

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@pipe119 use a soldering iron (I prefer a chisel tip for this kind of work), flux , solder and some desoldering braid. Heat your soldering iron. Apply flux to the solder bridge, apply some solder to your soldering iron tip. Now place the braid over the bridge and use your iron to melt the solder from the solder bridge. The solder will soak into the braid. Keep it to a point that the solder is still liquid while you then remove the braid. Something like this might be useful for you.

Your app will only work if those circuits are still working. Don't be surpised if it does not. Let us know how this all works out for you.

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It’s been quite a few years since I worked on one of these, so my memory is a bit foggy. In looking at the guide images it’s clear there is no solder bridge across the two pins. There might be a trace shared but clearly not a solder bridge!

So if you see a solder bridge then it needs to be removed to restore the original Apple design.

Update (08/29/24)

As to the original issue of the system running hot, most likely the heat sink coolant has leaked out so the system is not effectively cooling the CPU chip.

I would start off cleaning the dust buildup on the fan blades and heat sink fins so the you have a known baseline.

Then see if refreshing the thermal paste helped an then lastly replacing the heat sink.

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I own one of these machines and just checked how the pins are. They are not soldered across on mine. Pretty good chance if you remove the bridge it will function as normal.

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