ESP12F, cant get a relay to work with data from dht11

Question

i've been trying to build a system that detects in one room of the house the temperature using an esp8266 and a dht11 sensor, this esp sends the data to a webserver while the ESP12F grabs this data and should turn the relay on when a certain value is reached, however i can't get the relay to work, as soon as i upload the code, the led on the module turns but not at its full power, i tried with another code to see if it was just a faulty relay, but it works perfectly with the same connections. The code from the client side of the system is below:

#include "ESP8266WiFi.h"
#include "ESP8266HTTPClient.h"
#include "WiFiClient.h"

#include "ESP8266WiFiMulti.h"
ESP8266WiFiMulti WiFiMulti;

const char* ssid = "*******";
const char* password = "********";

//Your IP address or domain name with URL path
const char* serverNameTemp = "http://192.168.1.188/temperature";
const char* serverNameHumi = "http://192.168.1.188/humidity";
const char* serverNamePres = "http://192.168.1.188/pressure";

#include "Wire.h"
#include "Adafruit_GFX.h"
#include "Adafruit_SSD1306.h"

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

String temperature;
String humidity;
String pressure;

const int relay = 5;

float temp_int = temperature.toFloat();


unsigned long previousMillis = 0;
const long interval = 2000; 

void setup() {

  Serial.begin(115200);
  Serial.println();
pinMode(relay,OUTPUT);
digitalWrite(relay,LOW);

  // Address 0x3C for 128x64, you might need to change this value (use an I2C scanner)
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  display.clearDisplay();
  display.setTextColor(WHITE);
  int int_temp = temperature.toFloat();

  WiFi.mode(WIFI_STA);
  WiFiMulti.addAP(ssid, password);
  while((WiFiMulti.run() == WL_CONNECTED)) { 
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("Connected to WiFi");
}

void loop() {
  unsigned long currentMillis = millis();

  if(currentMillis - previousMillis >= interval) {
     // Check WiFi connection status
    if ((WiFiMulti.run() == WL_CONNECTED)) {
      int int_temp = temperature.toFloat();
      temperature = httpGETRequest(serverNameTemp);
      humidity = httpGETRequest(serverNameHumi);
      pressure = httpGETRequest(serverNamePres);
      if(int_temp < 26){
        digitalWrite(relay,LOW);
      }
     else if (int_temp > 26){
      digitalWrite(relay,HIGH);
     }

      Serial.println("Temperature: " + temperature + " *C - Humidity: " + humidity + " % - Pressure: " + pressure + " hPa");
      Serial.println(int_temp);
      Serial.println(temperature.toFloat());
      display.clearDisplay();

      // display temperature
      display.setTextSize(2);
      display.setCursor(0,0);
      display.print("T: ");
      display.print(temperature);
      display.print(" ");
      display.setTextSize(1);
      display.cp437(true);
      display.write(248);
      display.setTextSize(2);
      display.print("C");

      // display humidity
      display.setTextSize(2);
      display.setCursor(0, 25);
      display.print("H: ");
      display.print(humidity);
      display.print(" %"); 

      // display pressure
      display.setTextSize(2);
      display.setCursor(0, 50);
      display.print("P:");
      display.print(pressure);
      display.setTextSize(1);
      display.setCursor(110, 56);
      display.print("hPa");

      display.display();

      // save the last HTTP GET Request
      previousMillis = currentMillis;
    }
    else {
      Serial.println("WiFi Disconnected");
    }
  }
}

String httpGETRequest(const char* serverName) {
  WiFiClient client;
  HTTPClient http;

  // Your IP address with path or Domain name with URL path 
  http.begin(client, serverName);

  // Send HTTP POST request
  int httpResponseCode = http.GET();

  String payload = "--"; 

  if (httpResponseCode>0) {
    Serial.print("HTTP Response code: ");
    Serial.println(httpResponseCode);
    payload = http.getString();
  }
  else {
    Serial.print("Error code: ");
    Serial.println(httpResponseCode);
  }
  // Free resources
  http.end();

  return payload;
}