No response in Serial Monitor from es8266 with Arduino nano I have exactly this model of esp8266:

I removed Atmega328p IC from Arduino, and powered Arduino with USB cable. After all, I made this connection combinations:
1)
ESP Tx &gt; Arudino Tx
ESP Rx &gt; Arduino Rx
ESP 3.3v &gt; Arduino 3v3
ESP Dh_cp &gt; Arduino 3v3
ESP Gnd &gt; Arduino Gnd
ESP GPIO0 &gt; GND

2)
ESP Tx &gt; Arudino Rx
ESP Rx &gt; Arduino Tx
ESP 3.3v &gt; Arduino 3v3
ESP Dh_cp &gt; Arduino 3v3
ESP Gnd &gt; Arduino Gnd
ESP GPIO0 &gt; GND

3)
ESP Tx &gt; Arudino Tx
ESP Rx &gt; Arduino Rx
ESP 3.3v &gt; Arduino 3v3
ESP Dh_cp &gt; Arduino 3v3
ESP Gnd &gt; Arduino Gnd

4)
ESP Tx &gt; Arudino Rx
ESP Rx &gt; Arduino Tx
ESP 3.3v &gt; Arduino 3v3
ESP Dh_cp &gt; Arduino 3v3
ESP Gnd &gt; Arduino Gnd

I checked both 9600, and 115200 baud, but on any of them I did not get a reply to the AT command. Have I done something wrong? I get weird characters when disconnecting ESP's GND wire, so some communication exists.
If it is not a genuine Arduino (Chinese clone probably) and it has the CH340 USB to Serial converter chip, then it will not work as the digital Signal on TX does not get pulled to ground when transmitting a digital LOW, (if that's the right way to say it). There seem to be resistors on the board that cause this effect, or something. I do not guarantee that this is your problem but it's highly likely.
Use an FTDI USB to Serial board or similar and you might have better results.