My nest thermostat heat is set to 70 degrees and the house is 64 degrees.

[lashk90]

My nest thermostat heat is set to 70 degrees and the house is 64 degrees. The font is glowing orange and says the heat is on but the furnace is not running. I have to set my heat below the room temperature and then back above for the furnace to go on. My house will only be heated to 67 degrees and shut off. I then have to turn my thermostat below the room temperature and back above the room temperature to call the furnace on again. I have reset my thermostat and turned my furnace on and off, but I have not found any other solutions on the forum. Has anyone ever fixed this issue?

[CoolingWizard]

@lashk90 , 

First of all you need to perform proper diagnostics of the situation. You’re applying a workaround, but we need to first determine where the problem lies. If as you say the next thermostat is orange and says heat is on you need to go to the air handler and measure the current available on the W wire and see if if a heat call signal is being sent by the thermostat. Set your digital voltmeter to measure alternating current and then check between the W wire and the C terminal and you should read a voltage of approximately 24 V +/- 4 V.  if you indeed measure any voltage and the furnace is not running, the thermostat is sending a single then the problem lies in the furnace  please report back what your findings are

AC Cooling Wizard

[lashk90]

Thank you, I will get a voltmeter and give that a shot. If it isn't sending any voltage to the furnace what would you suggest next? 

[CoolingWizard]

@lashk90 ,

I there is zero to no voltage then the Nest Thermostat may have either a defective relay or a software defect. 

AC Cooling Wizard

[lashk90]

Okay, thank you for letting me know. I am going to be checking that today. Is there any way to fix a defective relay or software defect? There is not a software update available. I will likely be replacing it with a Honeywell if there no voltage. 

[CoolingWizard]

@lashk90 ,

The internals of the Nest Learning Thermostat are not serviceable.  if you have owned your thermostat for less than one year, you can get it replaced under warranty. If you had a nest pro who installed it you get a three year warranty.

AC Cooling Wizard