Imac mid-2011 CPU fan low speed (420 rpm)

Hi everybody (sorry for my poor english but i am french from Bordeaux...)

I am the happy user of an imac 27" mid-2011 i5 2.7 ghz (version 12,2) since 2012.

Recently, i noticed that the left high part of the screen heated a lot and made an apple diagnosis that obtained the error 4MOT/4/4000003: HDD-1487
I also installed MacFan who indicated 0 RPM for CPU fan.
I also replaced CPU fan with a resturbished one and in the same time installed an SSD on the first SATA port and leaved the original HDD on the second one.

Since this operation, i have the error 4MOT/4/4000002: CPU-391 and CPU fan which turns to 380-430 RPM but can't modify the speed with MacFan. The CPU temperature somtimes reach 70° C (158 ° F).

I red the problems of probe which can cause an acceleration of this fan, but nothing on a low speed.
I also wished to test the fan (maybe the resturbished is also altered ?) with a PWM prototype but didn't found any thing about the connector pin out of my imac version.

I am a little lost ...

Thank you for your help.

Welcome to our forums.

Your English is a lot better than my French.

The error you're receiving is a temperature sensor error. From your description, I can't tell if it's because the sensor itself is defective or because you installed an SSD in addition to the HDD. Why don't you disconnect the HDD as a test to see what the fans speeds are and the temperatures?

Your 2011 iMac actually has three sets of temperature sensors and fans: HDD, CPU, and Optical Drive. And yes, it's possible that the refurbished fan you bought is likewise defective.

chscag said:

Welcome to our forums.

Your English is a lot better than my French.

The error you're receiving is a temperature sensor error. From your description, I can't tell if it's because the sensor itself is defective or because you installed an SSD in addition to the HDD. Why don't you disconnect the HDD as a test to see what the fans speeds are and the temperatures?

Your 2011 iMac actually has three sets of temperature sensors and fans: HDD, CPU, and Optical Drive. And yes, it's possible that the refurbished fan you bought is likewise defective.

Click to expand...

Thx a lot for your advises. I'll try it this weekend and report you the results after.

Have a nice day !

Olivier