Do I have to pay the repairs for a faulty product?

Normally AppleCare warranty will cover the cost either the repair is within one year from the date of purchase

or you bought extended AppleCare warranty.

I would contact Apple Store for relevant information.

For info:

https://checkcoverage.apple.com

Section: Mac

https://www.apple.com/support/products/

A lot depends on who you take it to. An Apple Store will never charge for an evaluation for repair, whether it's in or out of warranty. In my experience they don't even require payment for fixes that don't require any repair parts.

An Apple Authorized Service Provider may be different. They're free to charge their own labor rates. Quite a few require the customer to agree to payment for a diagnostic, which may be waived (i.e. paid by Apple) if it's determined to be a defect that's covered under warranty. It's not much different than taking a car to a car dealer during the warranty period; many won't even look at a vehicle under warranty unless the customer agrees to pay for the diagnostic if the carmaker won't (when it's covered under warranty). Certainly the AASP program can be valuable for people who can't get to an Apple Store, but for me going to an Apple Store is the preferred way to seek a repair because I know I'm not going to be charged to just figure out what the problem is.