bugfix

src/fan_driver.h

@@ -114,7 +114,10 @@ static void fan_driver_compute_rpm(void) {
 static void fan_driver_control_loop(void) {
     // if we need to power down, disable power pin and return
     fan_driver_set_power(!fan_driver_powered_down);
-    if (fan_driver_powered_down) return;
+    if (fan_driver_powered_down) {
+        fan_driver_current_rpm = 0;
+        return;
+    }
 
     // see if fan stalled, set rpm to 0 and return if it is
     static uint32_t last_delta_idx = 0xffffffff;