diff --git a/src/main.c b/src/main.c
index f2dd498..09c5b1d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -10,14 +10,19 @@
 #define MOS03 PB2  // Lights Enable
 
 // PWM Devices
-#define FAN01 PD4  // Fan Peltier Hot Side Speed
-#define FAN02 PD5  // Fan Peltier Cold Side Speed
-#define HOT01 PD7  // Heating Temperature
+#define FAN01 PD4  // NF-12 Fan Peltier Hot Side Speed
+#define FAN02 PD5  // NF-A8 Fan Peltier Cold Side Speed
+#define FAN03 PD7  // NF-R8 Fan Heating Element Speed
+
+// Sensors
+#define AHT01 0x0  // Upper Sensor TWI Channel
+#define AHT02 0x1  // Middle Sensor TWI Channel
+#define AHT03 0x2  // Lower Sensor TWI Channel
 
 #define PWM_CYCLE_TOP  (F_CPU / 25000) // 25 KHz
 #define FAN01_MIN_DUTY (PWM_CYCLE_TOP * 0.2f)
 #define FAN02_MIN_DUTY (PWM_CYCLE_TOP * 0.2f)
-#define HOT01_MIN_DUTY 0
+#define FAN03_MIN_DUTY (PWM_CYCLE_TOP * 0.2f)
 
 static void SetPinDefaults(void);
 static void SetTwiChannel(int channel);
@@ -41,7 +46,7 @@ int main(void)
 
 	// PWM_Set(FAN01, 50);
 	// PWM_Set(FAN02, 50);
-	// PWM_Set(HOT01, 50);
+	// PWM_Set(FAN03, 0);
 
 	SetMosState(MOS01, false);
 	SetMosState(MOS02, false);
@@ -49,7 +54,7 @@ int main(void)
 
 	SetPwmValue(FAN01, 50);
 	SetPwmValue(FAN02, 50);
-	SetPwmValue(HOT01, 0);
+	SetPwmValue(FAN03, 20);
 
 	SetTwiChannel(0); // I2C Mux
 
@@ -68,24 +73,24 @@ static void SetPinDefaults(void)
 	// Initialize Pin Outputs
 	// ======================
 
-	// PB0: MOSFET #1 (Peltier)
+	// PB0: MOSFET #1 Peltier
 
 	DDRB |= BIT(PB0);    // Out
 	PORTB &= ~BIT(PB0);  // Low
 
-	// PB1: MOSFET #2 (Heating)
+	// PB1: MOSFET #2 Heating
 
 	DDRB |= BIT(PB1);    // Out
 	PORTB &= ~BIT(PB1);  // Low
 
-	// PB2: MOSFET #3 (Lights)
+	// PB2: MOSFET #3 Lights
 
 	DDRB |= BIT(PB2);    // Out
 	PORTB |= BIT(PB2);   // High
 
-	// PD4: PWM Peltier Hot Side
-	// PD5: PWM Peltier Cold Side
-	// PD7: PWM Heating
+	// PD4: PWM NF-12 Fan Peltier Hot Side
+	// PD5: PWM NF-A8 Fan Peltier Cold Side
+	// PD7: PWM NF-R8 Fan Heating Element
 
 	DDRD |= BIT(PD4) | BIT(PD5) | BIT(PD7);
 
@@ -95,9 +100,11 @@ static void SetPinDefaults(void)
 	TCCR2 = BIT(WGM20) | BIT(WGM21) | BIT(COM21) | BIT(CS20);
 	ICR1 = PWM_CYCLE_TOP; // 8000 MHz / 25000 KHz
 
+	// TODO: Get 25 KHz frequency for timer 3
+
 	OCR1A = FAN01_MIN_DUTY;
 	OCR1B = FAN02_MIN_DUTY;
-	OCR2 = HOT01_MIN_DUTY;
+	OCR2 = FAN03_MIN_DUTY;
 }
 
 static void SetTwiChannel(int channel)
@@ -168,7 +175,7 @@ static void SetMosState(int port, bool state)
 }
 
 // Port must be PD4, PD5 or PD7 and the value is
-// expected to be in the range between 0 and 100.
+// expected to be in the range between 0 and 100
 static void SetPwmValue(int port, int value)
 {
 	int n;