diff --git a/klippy/heater.py b/klippy/heater.py
index 5addfaca..359c80bd 100644
--- a/klippy/heater.py
+++ b/klippy/heater.py
@@ -65,14 +65,15 @@ class PrinterHeater:
             if (read_time < self.next_pwm_time
                 and abs(value - self.last_pwm_value) < 15):
                 return
-        elif not self.last_pwm_value:
+        elif not self.last_pwm_value and (
+                self.target_temp <= 0. or read_time < self.next_pwm_time):
             return
         pwm_time = read_time + REPORT_TIME + SAMPLE_TIME*SAMPLE_COUNT
         self.next_pwm_time = pwm_time + 0.75 * MAX_HEAT_TIME
         self.last_pwm_value = value
-        logging.debug("%s: pwm=%d@%.3f (from %.3f@%.3f)" % (
+        logging.debug("%s: pwm=%d@%.3f (from %.3f@%.3f [%.3f])" % (
             self.config.section, value, pwm_time,
-            self.last_temp, self.last_temp_time))
+            self.last_temp, self.last_temp_time, self.target_temp))
         self.mcu_pwm.set_pwm(pwm_time, value)
     # Temperature calculation
     def calc_temp(self, adc):