CHANGED HDD and NOW FANS work ALL the TIME (imac 7,1 - mid 2007)

Did you transfer the thermal sensor from the old drive to the new and reconnect it to the sensor cable?

If not, you will need to so that the System Management Controller can properly control the fan speeds.

If you did, then you may have damaged either it or one of several other sensor cables or connections.

See steps 19 thru 21 at > iMac Intel 20" EMC 2133 and 2210 Hard Drive Replacement - iFixit

Try downloading the > iStat Pro, a Dashboard Widget by iSlayer checking to see which fan is run amuck and which sensor reading is whacked out.

I only have a screen shot from my 2006 iMac and you may have a slightly different senor aray, but compare your readouts and see if anything there looks funny.

Humm.. the CPU fan, I expected to see a bad temp reading and the HDD fan maxed out?

I'm not sure because I don't have that same iMac, but it looks like maybe your missing the ODD (Optical Disk Drive) and/or the Mem. Controller sensor(s)...?

Recheck all the sensor cable connections for a broken connector or loose wire. Next trace all of the wires back to the sensors to make sure that they are connected to the correct sensor and not pinched anywhere.

Hello.

I am iin the process of researching in order to replace HDD in mid-2007 24" iMac and have come across several disccusions regarding continuous operation of fans after replacing the original hard drive. Have you seen those?

Here is apparently what seems to be the best "fix" and might provide some help for you.

What I am trying to research is whether or not a WD Blue Caviar 1T model #WD10EALS 3Gbps has a different connector pin than the #WD10EALX 6 Gbps and if might might this avoid the temp sensor malfunction problem.

Going further, if I were to purchase either the WD Green or Black Caviar 1T models with 6Gbps will those connector pins be backwards compatible with the 2007 iMac (i've read they are) but will most certainly create the constant fan operating problem.

I will most likely repost this as a new discussion once I get all the facts gathered into one place along with all the questions I have.

Brae

Brae,

Piggybacking on someone elses post may not get your question answered. Try reposting your own particular question.😉

Yes I was going to RRFS but ultimately got enough information to avoid having to do so. I'll just delete it if I can and after reading it it looks like I need to add the information on the fan control software just in case it helps someone else along the way.

But you are correct about piggybacking. I normally don't do that and was simply "thinking out loud" and should have cut all that out of there for sure.

brae

I had the same problem on my Mid 2007 iMac too after hard drive upgrade and finally found the culprit after 2 days! The fan noise was unbearable.

If the fan is running at full speed right after you press the power button, it may be because of damage to the LCD temperature sensor cable that runs along the edge of the LCD (tucked under a gap) to the little circuit board on the top left of the LCD. Since the sensor can't be read, the SMC defaults to a fail safe mode which sets the CPU fan (lower left of case) to max speed. (Download smcFanControl and raise the speeds of the other 2 fans, and you'll see that they're not maxed out... I've never heard them run actually...)

Apple really should have routed this cable differently as the whole LCD screen rests on it during diassembly while you disconnect those 3 connectors for the screen, then when you close the front cover it can get easily severed by the sharp machined aluminum! I found mine to have bare wires exposed.

I soldered mine back and the fan is back to normal speed. Hope this helps. FYI, the part number for this cable is 922-8236.

EYing

Thank you very much for that splendid piece of information. I have been trying to fix this fan problem for a few months now. Did not consider the wireing. That solved it. Put in a SSD and now everything is quiet and blindingly fast.

Wow, thanks for that. I just replaced the hard drive today and the CPU fan is going crazy. I opened it back up and sure enough I've severed that cable with the long bezel screw. There's no way I can successfully solder that myself, so I've ordered a new one.

I know you wrote this a few months ago but thanks for the reply and photo, it saved me probably many many hours of hassle.

EYing wrote:

I had the same problem on my Mid 2007 iMac too after hard drive upgrade and finally found the culprit after 2 days! The fan noise was unbearable.

If the fan is running at full speed right after you press the power button, it may be because of damage to the LCD temperature sensor cable that runs along the edge of the LCD (tucked under a gap) to the little circuit board on the top left of the LCD. Since the sensor can't be read, the SMC defaults to a fail safe mode which sets the CPU fan (lower left of case) to max speed. (Download smcFanControl and raise the speeds of the other 2 fans, and you'll see that they're not maxed out... I've never heard them run actually...)

Apple really should have routed this cable differently as the whole LCD screen rests on it during diassembly while you disconnect those 3 connectors for the screen, then when you close the front cover it can get easily severed by the sharp machined aluminum! I found mine to have bare wires exposed.

I soldered mine back and the fan is back to normal speed. Hope this helps. FYI, the part number for this cable is 922-8236.

EYing

Dude! You are the man. Exactly the same thing happened to me. I want to add some detail to this issue: The screw is the culprit. That string of 4 thin wires is wrapped in a protective sheath probably for this very reason, when placing the screen back into place, those wires need to be tucked way down below the edge of the monitor. Otherwise here's what happened to me:

Iplaced the screen in, screwed it down, connected all cables, etc. then when I went to screw the outer bezel back one small screw, as I was screwing it in, went through the protective sheath and actually cut into the wire. This caused a short and the machine shut off. Wouldn't start either. I removed everything and found the wire cut straight through. It was the screw that did it.

So glad you mentioned soldering it, that gave me the courage to do the same, I removed the entire cable from the monitor housing to see if I could free some slack, cut open the fabric shield around the wires, very delicately scraped off the rubber shield on the outside of the broken wire (1 of 4), twisted them together, soldered them, and then squeezed a very small piece of duct tape around them to protect the wires from shorting on another piece of metal.

Made the connection at the sensor on the top of the monitor, then pushed the cable back into place, replaced the monitor, connected the bottom connector (labeled LCD something or other), and then using the plastic tool I got from ifixit pushed the cable down away from all screw ports very gently. Got everything back together and boom, totally works.

When replacing iMac screens, be very careful of that delicate (all of them actually) cable, it's very easy to damage it and like a previous post mentioned, it doesn't ship as a seperate part, so they're not super easy to find. I'm going to buy one today just so I have it in case my repair doesn't last.

Like another poster mentioned, this is the part in case you need to identify it (your model may be different than mine, I have a 24" dual 2.4 from late 2007.

Part: iMac Intel Aluminum 24" LCD Display Temp Sensor Cable .works in: iMac (24-inch Mid 2007)iMac (24-inch Early 2008) 2.4/2.8/3.06GHz.Apple part#922-8236.60

I'll also mention, this is the third drive in this iMac, the Seagate that Apple replaced for me last year died in less than a year. I also saw where the person who replaced the drive reviously nearly cut ther very same cable down by the bottom of the machine near the fan. That means even the apple tech or quite possibly the original assembler of this device had the exact same issue.

Thanks guys, I was so close to giving up.

EYing - Just to say thank you so much! I did exactly the same thing. I'm surprised none of the iFixIt guides mentioned this potential issue. I've just soldered it so hopefully that'll do the trick...