The pair, who both represent the Portuguese national team, have both played for Sporting CP and Man Utd, with Fernandes joining the Old Trafford side to much fanfare at the start of January.
Ronaldo joined the club in 2003 before eventually moving to Real Madrid for a world record £80m at the time a few years later.
Fernandes spoke to his compatriot for advice before moving to the Premier League, and he says they still talk all the time about United.
"Of course, I spoke with Cristiano after and he spoke very well about the club. I spoke with him some days ago, again," Fernandes told the official Man Utd site.
"Every time I speak with him, he asks me how Manchester is and if everything is okay. Everyone knows he spent a lot of time in Manchester and he has consideration for the club.
"He likes the club, I think he won his first Ballon d'Or here, so it's a club who've marked him, for sure."
Since arriving at Man Utd, Fernandes has already become a key member of the starting XI, and has also been vital in Paul Pogba's revitalisation in a United shirt,
In 27 appearances, he contributed 20 goals via 12 goals scored himself and eight assists.