4th Gen Thermostat not kicking on Heat Pump

[SamH53]

I have replaced my Honeywell Thermostat with a new Nest learning thermostat. I followed the prompts on the Google Home app during set up. The heat did not turn on last night and when I checked this morning I got a N407 O/B wire not detected error code. I have checked that the wire is inserted fully and stripped correctly. The Air handler and Heat pump both turn on however I am not getting any hot air. I have switched between O wire and B wire in the Google home app with no change. My system previously ran fine with the Honeywell thermostat. 

[CoolingWizard]

@SamH53 , the conventional heat pump as you are aware, is either a Type O or a Type B.  The N407 error that was reported by the Google Nest Learning Thermostat Gen-4 lets you know the the wire attached to OB does to energize properly.  This could indicate a failed ekectrical coil on the outdoor unit reversing valve solenoid. 
You can easily test for this using a multimeter. Do you own a multimeter? 

The Cooling Wizard

[SamH53]

Good evening I do have a multimeter. I can test the voltage going to the solenoid. I traced the wires from the reversing valve solenoid to the circuit panel. I will be testing for 24v AC? Would the Nest thermostat cause this issue? If the solenoid worked with the previous thermostat what would cause the malfunction? Thank you for your assistance it is very much appreciated Sir!

[CoolingWizard]

@SamH53 

You need to use the nest thermostat to put it to system in heating mode, then go to the air handler itself, set a meter to measure AC voltage, put one lead on the common of the control board put the other lead on the OB or O on the control board. See if you see output voltage coming on the O which would be coming from the thermostat.  if you receive no voltage from the thermostat, try this, switch your system mode at the thermostat to cooling and turn it on again. Go check the voltage if voltage is present at the air handler on the O wire between common and oh then your system is set up for cooling, and not for heating. this is where you change the B to O or vice versa. we’re trying to make sure that the nest thermostat does energize the O wire. If he gets no voltage on either cooling or heating at the O wire and it is defined in the thermostat as a heat pump, then there is a problem with the thermostat  

Type O heat pumps energize the O wire for Cooling by default these systems are Heaters.  Type B heat pumps energize the O wire to get Heat.  By default B models are air condoners. I hope my answer helps you to understand your system better. 

The Cooling Wizard