My heater works fine when I set the temperature to 69 and the temperature hits the desired temp it shuts off, then about 2 mins later the blower turns on like the heater is going to start up again, but since the desired temp is still satisfied the heater never comes on, the unit recognizes the fact that the system is satisfied so it then shuts off the blower.

  • By the way this goes on throughout the day, I tried changing the T-Stat and the same thing happens. There is also a 1 degree differential in the settings, it has always been like that and I have never had this issue.
    – Anthony
    Dec 20 '18 at 22:55
  • This should be added to your post and not as a comment. Also, you never asked a question so please do so. I assume you're wondering why it turns back on. Dec 20 '18 at 23:08
  • What make and model is said heater? Dec 21 '18 at 0:34

Welcome to DIY!

The blower runs when the heat exchanger goes over a set temperature and turns off when it goes under it as I bet you already know. However, heat is still transferring from where the fire was burning so it can warm back up and turn back on for a minute or so. The blower doesn't care if your thermostat is satisfied or not as it goes by it's own temperature control to make sure the furnace doesn't get too hot. That is probably your issue.

  • I would have to get back to you on the make and M# on the heater. But the blower motor comes on quit a few times and this has never happened before, so it doesn't sound like it would be to hot inside the furnace for the blower to come on so many times. I would think that the fan limit switch would be bad or maybe a circuit board, I will have to get into the attic and get the info of the unit.
    – Anthony
    Dec 21 '18 at 1:42
  • 1
    I believe hazardousglitch is saying there may be a sensor that detects heat and it is turning on the fan. If this sensor is getting flakey it could be the cause. I was thinking the same thing.
    – Ed Beal
    Dec 21 '18 at 18:23

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