Thermostat off and heat is still on

[8475nester]

Hello,

I installed the nest thermostat earlier this summer and here is the original thread that shows the current wiring.
https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-Thermostat-for-split-system/td-p/429101

The HVAC is Trane XR heat pump system and during summer, the system worked great with cooling. Last night I turned the heating on and now it won't shut off. The nest thermostat shows the system is off but the HVAC is running and hot air is coming out from the vents. If I turn it to cooling, it starts blowing cold air; however turn it off in the app won't stop the HVAC.

Appreciate the help. Thanks!

[8475nester]

 

  

[8475nester]

@CoolingWizard - Any thoughts on this issue since you helped me the wiring last time?

[CoolingWizard · Accepted solution]

@8475nester , I took the time to look at your photo on Google drive, it appears you do not have a heat pump. Your wires being used on your old thermostat were Rc/R, W, B, Y, G, S1, S2. The S1 and S2 wire are to be ignored and the Nest Thermostat  does not need them.  The B wire is more than likely used as the Power Common.  You should  it have any wire connected to the O/B of the Nest Backplate. 
Your NEST wire should be as follows:

Red Wire connected to RC

White Wire connected to W1

Green wire connected to G

Yellow Wire connected to Y1

Blue Wire connected to C

This system appears to be a conventional HVAC system with a Forced Air Furnace and an Air Conditioner condenser unit outdoors.

AC Cooling Wizard

[8475nester]

@CoolingWizard - I have a nest 1st gen thermostat and don't have W1 wire. Do you mean White Wire connect to W and your sentence above " You should  it have any wire connected to the O/B of the Nest Backplate. " - do you mean, I shouldn't have any wire connected to O/B?

Do I need to change any setting on the app as well?

[8475nester]

I made the change and remove the White wire from 0/B to W and now I can't see the heat option on the thermostat or in my app. The W wire is not detected. 

[CoolingWizard]

Can you do a big favor and get the model number off of your outdoor unit please? I want to look it up and verify its capability. 
 As to the heat keeps running, there are multiple possibilities.  A step by step analysis is required to determine why this is happening. On a heat pump, there is a Defrost Control Board (DFC) in the outdoor unit, and this DFC can be wired to the indoor air handler to signal a defrost cycle is running in which case the the air handler turns off the blower or, activates the electric auxiliary heat.  If the DFC is bad, it might be causing this running on problem.  

Things I need to know to help you best. I need the model number of the indoor air handler and the outdoor unit.  

AC Cooling Wizard

[8475nester]

@CoolingWizard - Indoor air handler is Trane XV80 (Model # 2TXCC060BC3HCAA) - B could be R as some alphabets are scratched up.

Outdoor is XR13 (Model # 2TTR3060A1000AA)

Should I reset the nest to factory settings and maybe it will detect the heat?

[CoolingWizard]

The XV80 model number is the Cooling Coil only. However, the XV80 is a gas furnace.  And the XR13 2TTR series is not a heat pump. This is an R22 based straight cooling system. You have a 5-ton cooling system. Your heating system is a gas furnace.  We need to reconfigure your Nest Thermostat and change the system heat type is forced air and the Heat Source is GAS.  This means the white wire must be on W.  To change the HVAC system equipment type settings, you must do it at the Nest Display. Do you need my assistance to make these changes?

AC Cooling Wizard

[8475nester]

@CoolingWizard - I factory reset the thermostat and redid the wiring. Here is what the setup looks like. Heating is working and fan does stop when it's turned off. I haven't tried cooking yet and confirming if this looks correct?

 

 

 

[CoolingWizard]

@8475nester , normally when it comes to a efficient gas furnace like that and normally you don’t turn on the activate of the blower. What happens is the controller in a gas furnace will not turn the blower on until the gas is lit and it is already got the heat exchanger heated up to 250°. I would recommend that you go back to your settings and turn off the the fan blower under heating forced air

AC Cooling Wizard