ADC doesn't work properly PIC microcontroller

#include <xc.h>

// Config word
#define _XTAL_FREQ   2000000 // set it to match internal oscillator

/*config1 and config2 settings*/
 // CONFIG1
#pragma config FOSC = INTOSC // Oscillator Selection (INTOSC oscillator: I/O function on CLKIN pin)
#pragma config WDTE = OFF // Watchdog Timer Enable (WDT enabled)
#pragma config PWRTE = OFF // Power-up Timer Enable (PWRT disabled) (turned on!)/
#pragma config MCLRE = OFF // MCLR Pin Function Select (MCLR/VPP pin function is MCLR) (turned off)
#pragma config CP = OFF // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = ON // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = ON // Internal/External Switchover (Internal/External Switchover mode is enabled)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)

// CONFIG2
 #pragma config WRT = OFF // Flash Memory Self-Write Protection (Write protection off)
 #pragma config VCAPEN = OFF // Voltage Regulator Capacitor Enable bit (Vcap functionality is disabled on RA6.)
 #pragma config PLLEN = ON // PLL Enable (4x PLL enabled)
 #pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
 #pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
 #pragma config LPBOR = OFF // Low Power Brown-Out Reset Enable Bit (Low power brown-out is disabled)
 #pragma config LVP = OFF // Low-Voltage Programming Enable (Low-voltage programming enabled) (turned off)/


// Do the ADC convertion only for the channel indicated
// result of ADC is returned
 unsigned int ReadADC(unsigned char channel)
{
     unsigned int AN_Val;
     unsigned int bit_val;

   

     // automaticaly determines the input channel it will read the value from
     switch (channel)
         {
         case 1: // AN1 1000 0101
             ADCON0 = 0x85;                // bit0: ADC enabled
                                          //bit6-2: AN1 enabled for analog input
                                        //bit7: set for a 10-bit result(when its 1)
             break;
         case 2: // AN2 1000 1001
             ADCON0 = 0x89;
             break;
         case 3: //AN3 1000 1101
             ADCON0 = 0x8D;
             break;
         case 4: //AN4 1001 0001
             ADCON0 = 0x91;
             break;
         default: // Any other value will default to AN0
             ADCON0 = 0x81; // (1000 0001) - AN1 set up ADC ADCON0

 // sets the ADCON0 register for each port depending on the value of channel.
 // the result is 10-bit , The ADC is set to on, No convertion is in progress

         } // switch (channel)

     // Channel selected proceed with ADC convertion
    __delay_us(20); // sampling time
    ADCON0 = ADCON0 | 0x02; //This sets the go/!done bit that starts conversion. Bit will be cleared when ADC is complete
    while (ADCON0 & 0x02); //wait here until conversion is complete
    bit_val= ADRESH; // store upper 2 bits in a 16 bit int
    AN_Val = ((bit_val << 8) + ADRESL) & 0x03ff;// store the ADRESH into the 16 bit int then split it up 8 spaces after that add the ADRESL values using the and operator then clear any signed bits
    return AN_Val;
} // int ADC(unsigned char channel)



void main (void){

  //** Initalise Ports FOR ADC **//


  unsigned int AN1_Result;
  unsigned int AN0_Result;
  unsigned int AN2_Result;

  //** Initalise Ports FOR ADC **************************************************************//
     PORTA = 0x00; //Set ports to low
     PORTB = 0x00;
     TRISA = 0xFF; //Port A is all inputs. (set to 1)

     //** Set Up ADC Parameters **//
     ANSELA =0x2F ; // (0b00101111)All AN0-AN4(RA4 and RA7 have no ADC) of register A are set to analog input

     ADCON1 = 0xD0; // (0b11010000)
                    //format setup see page 182 of datasheet
                    // bit7: set for 2'complement format
                    // bit6-4 : set FOSC/16
    //********************************************************************************************//
 

  PORTC = 0x00;
  TRISC = 0x00; //Port C all output
  
         while(1){
       // __delay_us(10);
        AN0_Result = ReadADC(1);
        if(AN0_Result > 500){    // when the voltage is passed 2.5(almost) volts these two LEDS should come on.
                /*Turn these LED on*/
                LATCbits.LATC2 = 1;
                LATCbits.LATC3 = 1;
                LATCbits.LATC4 = 1;
                }
        else{
                /*turn one LED on*/
                LATCbits.LATC4 = 0;
                LATCbits.LATC2 = 0;
                LATCbits.LATC3 = 0;

                }
    }
}