Abnormality of motor

This is how I would tecnically analyize this sentence.

Why - Because computer # 1 expereinced problem
Cause - Computer cooling fan malfunctioned which had caused the thermo breaker to trip when the thermocouple detected temperature reaching 28 deg c.
Fact - Technician has verified the cause.

So the following are possible as a service report statement:

The problem on computer # 1 was verified by the techician to be a defective fan motor which caused the heat to build up and tripped the breaker.  
The shut down of computer # 1 was caused by an abnormality in the cooling fan. Heat build-up tripped the thermo protective breaker.  

<<<>>>The abnormality of fan motor for computer no.1, which motor tripped as the operating temperature at 28C, has been vertified by technician.

Yes, the sentence sounded bumpy and stiff, aside from grammatical mistakes. Technical report needs to be clear and accurate. That's the reason I gave you the breakdown and the construction possibilities.
Tripping - is a terminology used sepcifically in the electrical field to mean "open circuit" by default. A motor can trip the breaker but does not trip itself. Unless it's a thermally protected motor which is not the case in personal computers. There are bigger cooling fans used in mainframe computers and large electronics which have resettable fuse or circuit breakers.
The relative clause usually requires no "comma".
Depending on the construction of the sentence, "Which" usually links the noun or pronoun to the clause. i.e. I've just moved to a new apartment which is only 10 minutes from my office.
In your constrcution, "fan motor" and "computer" were incorrectly linked to the realtive clause, in my opinion.