diff -r 712984fdd26b -r 5cf6f099c897 thermferm/thermferm.c
--- a/thermferm/thermferm.c	Thu Mar 17 23:28:29 2016 +0100
+++ b/thermferm/thermferm.c	Sat Mar 26 14:43:31 2016 +0100
@@ -1233,6 +1233,10 @@
 		    }
 		}
 
+		/*
+		 * Unit door state, default is closed.
+		 */
+		unit->door_state = 1;
 		if (unit->door_address) {
 		    rc = device_in(unit->door_address, &temp);
 		    if (rc == DEVPRESENT_YES) {
@@ -1247,16 +1251,13 @@
 			    	unit->door_state = 0;
 			    }
 			}
-		    } else {
-			unit->door_state = 1;
 		    }
-		} else {
-		    /*
-		     * No door switch, say door is closed.
-		     */
-		    unit->door_state = 1;
 		}
 
+		/*
+		 * Unit PSU state, default power is ok
+		 */
+		unit->psu_state = 1;
 		if (unit->psu_address) {
 		    rc = device_in(unit->psu_address, &temp);
 		    if (rc == DEVPRESENT_YES) {
@@ -1271,11 +1272,7 @@
 				unit->psu_state = 0;
 			    }
 			}
-		    } else {
-			unit->psu_state = 1;
 		    }
-		} else {
-		    unit->psu_state = 1;
 		}
 
 		/*
@@ -1651,19 +1648,19 @@
 			fprintf(stdout, "Final: PIDheat=%.2f PWRheat=%d  PIDcool=%.2f PWRcool=%d\n", 
 					unit->PID_heat->OutP, unit->heater_state, unit->PID_cool->OutP, unit->cooler_state);
 
-		    if ((unit->heater_address || unit->cooler_address) && unit->fan_address) {
-			/*
-			 * If there is a heater or cooler and we have a fan, turn fan on if
-			 * cooling or heating. The Fan has a start/stop delay.
-			 */
-			if ((unit->heater_address && unit->heater_state) || (unit->cooler_address && unit->cooler_state)) {
+		    /*
+		     * If there is a fan, and the unit door is closed, and the unit should be doing
+		     * something, then turn on the global fan.
+		     */
+		    if (unit->fan_address) {
+			if (unit->door_state) {
 			    if (unit->fan_wait < unit->fan_delay) {
-				unit->fan_wait++;
+			    	unit->fan_wait++;
 			    } else {
-				if (! unit->fan_state) {
+			    	if (! unit->fan_state) {
 				    syslog(LOG_NOTICE, "Unit `%s' Fan Off => On", unit->name);
-			    	    unit->fan_state = 100;
-				}
+				    unit->fan_state = 100;
+			    	}
 			    }
 			} else {
 			    if (unit->fan_wait > 0) {
@@ -1675,11 +1672,9 @@
 				}
 			    }
 			}
-			if (unit->door_state)
-			    device_out(unit->fan_address, unit->fan_state);
-			else
-			    device_out(unit->fan_address, 0);
+			device_out(unit->fan_address, unit->fan_state);
 		    }
+
 		} else {
 		    unit->PID_cool->Mode = unit->PID_heat->Mode = PID_MODE_NONE;
 		} /* fridge beer or profile mode */
@@ -1716,6 +1711,9 @@
 #ifdef HAVE_WIRINGPI_H
 		piLock(LOCK_LCD);
 #endif
+		/*
+		 * Write 4 rows to the LCD to display the unit state
+		 */
 		lcd_buf_write(row++, "Unit %d: %s          ", LCDunit, UNITMODE[unit->mode]);
 		lcd_buf_write(row++, "%s                   ", unit->name);
 		lcd_buf_write(row++, "%c%5.1f\2 A%6.2f\1    ", LCDstatC, LCDspH, LCDair);