Hi,
I have a Hyundai sonata 2006 model. Mileage is about 126k. I am facing a strange rattling issue with my car when I accelerate. It does not happen when I start the car for the first time in a day or while parking. But when I park the car and start it again after some time, and when I accelerate I hear a rattling noise and the engine faces a lot of strain. Sometimes, I had to stop the car and wait for some time before starting it again.

I have observed this when I run the AC on or when it is too hot outside. Does not happen in cold weather. Is it a common problem? Would be helpful to know how to get it fixed or what kind of diagnostic tests should I be asking from the mechanic?

 

If you can. tell the shop all the info you have noticed, this could help save some time looking in areas where there is no problem and concentrate on the areas you provided some clues as to what may happening.
It is important to mention the things you noticed when using the A/C, it might save some time and $$$.