Turned off the car pulled out the key and noise is coming from under the hood.

What is your question?

Just had the timing belt replaced. 100,500 miles. I inserted the key and started the car then turned it off again and the noise was gone. This has never happened in the 2 yrs I have had the car. Also, after an A/C diagnostic test I was told I need the A/C compressor replaced and the mechanic disconnected the a/c said if I continue to use it it will cause more repairs. Is any of this related to the noise I heard. It happened again yesterday and I raised the hood and the car was hot and it may be a fan of some kind blowing. Do not think the engine was running.