Fan running in iMac iMac (21.5-inch, Mid 2011) OSX 10.13.6
runs fine, but just noticing whirring sound like a fan from back of iMac. Can this be replaced/repaired?
iMac 21.5″, macOS 10.13
+1 on Mal-S's suggestion of an SMC reset.
If the SMC reset does not correct the issue, best next step to run Apple Hardware Test (AHT). That model has three fans:
- CPU fan
- optical drive fan
- hard drive fan
Why? The hard drive fan has a tendency to fail in that specific model. If it does, the other fans go to "full speed ahead" to compensate. Think of it as wagon pulled by three horses. If one horse can no longer work, the other two have to work harder to maintain the same speed.
AHT will show whether the fault is a fan motor or a bad temperature sensor, and the codes follow those can tell us which sensor or fan is acting out.
How to use Apple Hardware Test on your Mac - Apple Support
If it throws a code, the code will be rather cryptic and Apple have not published a "secret decoder ring" to translate. However, several of us graybeards know the codes, so we can translate if you post the code here.
⚠️ A heads-up regrading repair if needed:
<>FAN MOTOR ERROR: Unless the fan is only physically jammed and not dead, the fan needs replacing. This is a doable but very difficult fix.
Although the 2011 iMacs were the last that could be opened without breaking a glued case seal, servicing the hard drive fan is about as far from trivial as you can get. One of the popular self-service sites rates it as difficult, requiring almost a complete gutting of the computer to access. For most users thisis not an do-it-yourself fix.
<>SENSOR ERROR: Depends on the sensor, but most sensor failures require a new logic board. Our 2011 iMac 21.5 is still a workhorse within limits but I would not incur the cost of a new logic board for an obsolete 12-year old computer.
