Servo issue, won't go into negative range
First of all Servo.write(int) takes a value ranging from 0 to 180 degrees. 
Then, servos themselves can only move from 0 to 180 usually. Some can do more, some can do less. But regardless of how much a servo actually moves, you should expect that doing Servo.write(0) the servo would rotate all the way to one side, doing Servo.write(180) it should go to the other side, doing Servo.write(90) it should stay in the middle.

Also, lcd.setCursor(5, 1); is basically useless as the lcd driver itself would advance the cursor as the previous characters are written. Just do lcd.print("= "); if you want an additional space between the equals symbol and the number