Nest 3rd Gen Thermostat does not heat

[Kevboost]

Can anyone help? I am at my wits end. I'm nearly 99% positive i have this thing wired correctly. The Fan, cooling and aux heat work. Only when i call for heat, it wont work. As soon as i put the old thermostat back on, everything works great. 

Old Thermostat wiring 

How i have it wired currently 

[Sky-Hou]

Please try changing the white line from W2 to W1.

[Zero_Integer]

I tried switching between W1 and W2 and switching between O and B even though we are sure it’s B. Nothing works 

[Kevboost]

I tried it.. it didn't work.

[Derickf]

Hi folks,

Thank you for posting in the community. I'm sorry to hear that your Nest Learning Thermostat (3rd gen) is failing to activate the main heating function when a call for heat is initiated, even though the fan, cooling, and auxiliary heat all operate correctly. I appreciate you confirming that your HVAC system works fine with your old thermostat, and you provide the picture of the wiring on your previous and new thermostats. I'm happy to assist.

@Sky-Hou, Thanks for jumping in.

To gather the necessary information, please answer the following questions:

• Have you tried to perform a factory reset on your Nest Learning Thermostat (3rd gen) to discard a setup issue?
• What other strange symptoms have you experienced since the problem started?
• Are there any error messages on your Nest Learning Thermostat (3rd gen) or Nest app?

I'll be waiting for your reply.

Best regards,

Derick.

[Kevboost]

1. Yes, i have performed the factory reset.

2. That's the only strange symptom. Heater wont turn on. Everything else works fine. I ruled out my wiring as the issue and have put the old thermostat on and it works just fine. 

3. There has not been any error messages.