using AT comands with arduino code

Using Arduino Project Guidance
#1

I've been trying to talk with a serial module and use AT commands that need "both in nl and cr" but through the code. but when I write Serial.write("AT\r\n") does not receive it. "
would could I do to fix it?

#2

How about

Serial.println("AT")

println() prints a CRLF sequence after whatever you pass it.

#3