Runaway fan - Temp sensors on Display/LCD on Late 2013 27" iMac ME088LL/A?

[1611mac]

For reasons not important here I had to remove the Display/LCD assembly from my late 2013 27" iMac (ME088LL/A). The Display/LCD assembly currently has all wire/harness connections unconnected while I run off an an external 27" monitor. However, the fan/blower runs at high speed now constantly. Is there some type of temperature sensor on the Display Assembly? Why would the fan/blower run at high speed without a display? (The display is on the Mac now an taped down but as I said, there are no connections to it.



The iMac works great this way using an external monitor but obviously I don't want the fan/blower to run at 100%. It is extremely loud, even with the display on the unit and taped down.



Thanks in advance for you answers and input.

 

[Cory Cooper]

Hello and welcome.

As you have found out, iMacs aren't designed to be user-serviceable, especially the more recent ones. With each generation, they become more difficult to open up, and they contain less individual parts which can be replaced.

That said, yes, all iMacs have LCD temperature sensors built-in, but the newer models don't have a separate cable, as It is included in the power or data cable. Since your iMac's fan is running full on, this would be the cause, unless there are other cables that haven't been reconnected properly, or something internally has become damaged. iMacs aren't designed to be run "internally headless."

Have you tried running Apple Diagnostics to test for any "other" hardware issues?

Hope that helps,

C

 

[1611mac]

I discovered that the sensor in question is actually connected to the display assembly itself. I'm now using fan control software to control the fan. This isn't ideal but it's a very tenable temp solution until I replace the display. Thanks!