Serial Monitor Stops Printing Data After Some Time: Using Arduino to Control Solenoid Valves

Projects General Guidance
2

This is my code FYI:

#include <LiquidCrystal.h>
#include <DHT.h>

#define DHTPIN 5    
#define DHTTYPE DHT22  


const int rs = 12, en = 11, d4 = 10, d5 = 9, d6 = 8, d7 = 7;
const int RELAY1_ENABLE = 3;
const int RELAY2_ENABLE = 4;

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
DHT dht(DHTPIN, DHTTYPE);

float hum;  
float temp; 

void setup() {
  // Declare pins as output:
  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  pinMode(RELAY1_ENABLE,OUTPUT);
  pinMode(RELAY2_ENABLE,OUTPUT);
  digitalWrite (RELAY1_ENABLE, HIGH); 
  digitalWrite (RELAY2_ENABLE, HIGH); 
  Serial.begin(9600);
  dht.begin();  

}

void loop() {
    
//Read data and store it to variables hum and temp
hum = dht.readHumidity();
temp= dht.readTemperature();  


if (hum < 88 ){

if (!Serial){
  Serial.end();
  delay(100);
  Serial.begin(9600);
}

digitalWrite (RELAY2_ENABLE, LOW); // Relay 1 swtiches on when pin is set to low
digitalWrite (RELAY1_ENABLE, HIGH); // Relay 2 swtiches off when pin is set to high


lcd.begin(16, 2);
lcd.print("Bubbling");

lcd.setCursor(0,1);
lcd.print("T:");
lcd.print(temp);
lcd.print(" ");


lcd.print("RH:");
lcd.print(hum);

Serial.println(temp);
Serial.println(hum);


delay(15000);



}


else if (hum>88){

if (!Serial){
  Serial.end();
  delay(100);
  Serial.begin(9600);
}

 
digitalWrite (RELAY1_ENABLE, LOW); // Relay 2 swtiches on when pin is set to low
digitalWrite (RELAY2_ENABLE, HIGH); // Relay 1 swtiches off when pin is set to high


lcd.begin(16, 2);
lcd.print("Drying");

lcd.setCursor(0,1);
lcd.print("T:");
lcd.print(temp);
lcd.print(" ");


lcd.print("RH:");
lcd.print(hum);

Serial.println(temp);
Serial.println(hum);

delay(15000);

}

}