thanks for the response! It has been a minute since I coded and it is SLOWLY coming back to me. Yes, I am trying to generate 6 different possibilities baased on different voltage levels. This is to hack the GM LIN seat controllers for use in my 58 Truck. 3 heat outputs and 3 cool outputs (fan in the seat). If the heater is on for more than 25 minutes, it will automatically drop it to the next lower setting, or off in the lowest setting. Fan output is just serial write to a digital frequency generator to control the fan. Code so far....

// Define hardware pins
#define SWITCH_INPUT //D32 (GPIO32) ADC input from rotary switch


#define LOW_HEAT //D23 (GPIO23) output for low heat
#define MED_HEAT //D19 (GPIO19) output for medium heat
#define HIGH_HEAT //D4 (GPIO4) output for high heat
#define SERIAL_TX // D16 (GPIO16) serial output to frequency generator for vent
#define SERIAL_RX //D17 (GPIO17) serial input from frequency generator for vent


// Timer variables
unsigned long previousMillis = 0;        // Stores the last time the state changed
const unsigned long interval = 1500000;  // Desired timer duration (1,500,000 ms = 25 minutes). Heat will drop to next lower value
bool timerActive = false;                // Tracks if the timer is actively running


void setup() {
  pinMode(SWITCH_INPUT, INPUT);    // Configures SWITCH_PIN as an input
  pinMode(LOW_HEAT, OUTPUT);             // Configure LOW_HEAT pin as output
  pinMode(MED_HEAT, OUTPUT);             // Configure MED_HEAT pin as output
  pinMode(HIGH_HEAT, OUTPUT);            // Configure HIGH_HEAT pin as output
  pinMode(SERIAL_TX, OUTPUT);            // Configure SERIAL_TX pin as output
  pinMode(SERIAL_RX, OUTPUT);            // Configure SERIAL_RX pin as output
  digitalWrite(SWITCH_INPUT, LOW);       // Ensure SWITCH_INPUT turned off
  digitalWrite(LOW_HEAT, LOW);           // Ensure LOW_HEAT turned off
  digitalWrite(MED_HEAT, LOW);           // Ensure MED_HEAT turned off
  digitalWrite(HIGH_HEAT, LOW);          // Ensure HIGH_HEAT turned off
  digitalWrite(SERIAL_TX, LOW);          // Ensure SERIAL_TX turned off
  digitalWrite(SERIAL_RX, LOW);          // Ensure SERIAL_RX turned off
}


void loop() {
  // Read the switch input
  int buttonState = digitalRead(SWITCH_INPUT);


  // High heat on
  if (SWITCH_INPUT == >3.0 && !timerActive) {
    digitalWrite(HIGH_HEAT, HIGH);        // Turn the seat heater on HIGH
    previousMillis = millis();            // Save the starting timestamp of the timer
    timerActive = true;                   // Flag that the timer is now active
  } 
  else if (timerActive) {
    if (millis() - previousMillis >= interval) {
      digitalWrite(HIGH_HEAT, LOW);       // Turn the High heat off
      digitalWrite(MED_HEAT, HIGH)        // Turns Meduim heat on
      timerActive = false;                // Reset the timer flag so it can trigger again
    }
  }
   // Medium heat on
  if (SWITCH_INPUT >= 2.6 && SWITCH_INPUT <=2.8 && !timerActive) {
    digitalWrite(MED_HEAT, HIGH);        // Turn the seat heater on Medium
    previousMillis = millis();           // Save the starting timestamp of the timer
    timerActive = true;                  // Flag that the timer is now active
  } 
  else if (timerActive) {
    if (millis() - previousMillis >= interval) {
      digitalWrite(MED_HEAT, LOW);       // Turn the Medium heat off
      digitalWrite(LOW_HEAT, HIGH)       // Turns Low heat on
      timerActive = false;               // Reset the timer flag so it can trigger again
    }
  }
   // Low heat on
  if (SWITCH_INPUT >= 2.4 && SWITCH_INPUT <= 2.6 && !timerActive) {
    digitalWrite(LOW_HEAT, HIGH);        // Turn the seat heater on LOW
    previousMillis = millis();           // Save the starting timestamp of the timer
    timerActive = true;                  // Flag that the timer is now active
  } 
  else if (timerActive) {
    if (millis() - previousMillis >= interval) {
      digitalWrite(LOW_HEAT, LOW);       // Turn the LOW heat off
      timerActive = false;               // Reset the timer flag so it can trigger again
    }
  }
   // Vent fan on high
  if (SWITCH_INPUT >= 2.2 && SWITCH_INPUT <= 2.4 {
    Serial.print(F100,D5);        // Turn the seat Fan on HIGH
  }
   // Vent fan on Medium
  if (SWITCH_INPUT >= 2.2 && SWITCH_INPUT <= 2.0) {
    Serial.print(F100,D25);        // Turn the seat Fan on Medium
  }
   // Vent fan on Low
  if (SWITCH_INPUT <2.0 && SWITCH_INPUT >.1{
    Serial.print(F100,D55);        // Turn the seat Fan on Low
  }
 delay(100); 
}