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Heat is not turning on. Compressor turns on and cool air comes out.

Treeblanco
Community Member

Help. We have been on the line with Google support for over an hour and we still do not have a resolution. The agent seems to be reading from a script and puts us on hold every 5 mins. We are so frustrated.

Our issue is, when we turn the heat on, the compressor turns on and cool air comes out of the vent.  

Our wires are hooked up as such:

Y1  Yellow

G  Green

OB  Blue

W1  White

Rh  Red

Any assistance you can provide will be greatly appreciated. 

24 REPLIES 24

CoolingWizard
Silver Product Expert
Silver Product Expert

Can you provide us the make and model number for your heat Pump indoor and outdoor HAVC systems? Heat pump systems use an reversing valve I the outdoor unit the change the flow of refrigerant.  This is how a heat pump changes from Heating to Cooling or from Cooling to Heating.  When the reversing valve is not energized it said to be in it default system mode. Some default to hearing, some default to cooling. 
The Nest has the ability to be set up to energize the reversing valve (OB) with when cooling is needed or when heating is needed.  It sounds like your Nest need to be changed from how it is current set.  Can you post the picture of you your old thermostat before you removed the wires?

Ken, The AC Cooling Wizard

NestPro and HVAC company owner

Hello Ken, thank you for replying. Unfortunately, my husband deleted the picture he took of the old thermostat when he installed the Nest.

The make of our HVAC unit is Trane and model number is 2TTR3048A1000AA

Thank you!

Treeblanco,
That Trane model number is not a heat pump. The outdoor unit is a straight conventional Air Conditioner.  That means that your system has either a gas furnace or electric heat strips in the indoor air handler.  If you are are sure about the outdoor unit model number, then you need to remove the blue wire off of the O/B terminal. The picture below is from the Installation and Operation Manual for the Trane 2TTR3048A1000AA. I Added an annotation for the Power Common wire connection points. Do you and your husband own a Volt Ohm Meter?

You need to change your Nest Equipment configuration.  1, turn power off, pull your thermostat face off the back plate.  remove blue wire from O/B and move it to C, and move Rh red wire to Rc. 2. Reattach the thermostat face to the back plate.  Goto Menu, and select. rotate ring to Equipment and select. The thermostat will then display a picture of the back plate with the wires connected. You might see a yellow wedge over O/B and or C, and that’s OK. Select Continue. The thermostat will now display your system setup Select Continue. The thermostat will now display Equipment  Settings, rotate the dial and select heat type. The thermostat will ask you for what type of fuel your heating system is using. your choices are gas, electric, oil, propane, geothermal. Choose the correct one and press select. I bet it’s gas at your house. Now the thermostat will ask you what type of heating do you have. Your choices are forced air,  in-floor radiant, radiators. Yours is probably forced air.  Press continue.  Now, you will see Test. Choose Heat and start the test.  You should have heat now. Select done and exit.  

36CD370A-00B4-41A1-915E-CCB70A832528.jpeg

Ken, The AC Cooling Wizard

NestPro and HVAC company owner

Hello Ken, we switched the O/B wire to C and the Rh wire to Rc. We followed the steps you provided, however, we received an error code of E79. No power to common (C) wire detected. We are unable to get past it.

Oh, yes, our furnace is gas and forced air.

Thanks.

Chances are your Blue wire is not connected properly in the Furnace.  Do you have access to the Furnace?

 

Ken, The AC Cooling Wizard 

NestPro and HVAC company owner

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@CoolingWizard, thanks for the help!

 

@Treeblanco, how's it going with your Nest Thermostat? Still need our help?

 

Thanks,

Edward

We appreciate all the assistance Ken has provided thus far. Unfortunately, we were unsuccessful in getting it to work. When in test mode, the heat turns on. However, when in normal mode, the compressor turns on and cool air comes out. We can't figure it out. Any additional help you can provide will be greatly appreciated. Thank you.

Your heat pump needs to have the OB wire mode changed. Your particular case you need to change the current setting to the opposite setting. I know that sounds confusing so here is  some clarification. All heat pumps are manufactured to be either be heaters by default or air conditioners by default. To get them to go into the opposite mode you have to energize the O wire which in turn changes the reversing valve and makes a heater and air conditioner or an air conditioner heater.

Wake up your thermostat, rotate the dial to the menu and select, rotate the dial to equipment, select equipment, then rotate the dial to heat. It knows you have a heat pump so it will then show you window energizer reversing valve and that’s the O wire. Whatever the current setting is highlighted and change it.

Ken, The AC Cooling Wizard

NestPro and HVAC company owner

Turned thermostat on. Rotate to Settings (no menu), select. Rotate to Equipment, select. Equipment detected and picture of wiring configuration.

Y1  Yellow

G  Green

OB  Blue

W1  White

Rh  Red

continue. Your System: Heat pump heating, Auxiliary heating, Heat pump cooling, fan Select continue. Equipment settings: Heat type (forced air), Heat pump (O is checked) select. It then asks, "Use the Heat pump if the outdoor temperature is above: [always]

I couldn't figure out how to attach pictures so I hope this makes sense. 

In the third step, where it showed O is checked, did you change that to B? The task was to take whatever it was and change it to the other. 
Ken, The AC Cooling Wizard 

NestPro and HVAC company owner

Treeblanco
Community Member

Hello Ken. Thank you for your patience with us. We finally gave in and called someone. Turns out our furnace needed additional wires which was why there was no power going to the C wire. My husband is happy now. Thank you once again!!!

Thank you for the reply. So, the heating is working now as well? The original reported problem is the system blows cold air when in heat mode and we were trying to help correct that. 
Ken, The AC Cooling Wizard

NestPro and HVAC company owner

Hi Ken,

 

I'm also having the same issue w the nest continuing to show a heat pump and no selection as to type of fuel.  I'm running off of gas.  I'm thinking either I'm missing something silly or the nest has an issue with it's firmware.  Any help would be appreciated, I had to install an older thermostat just to get some heat in the house my little boy is freezing 

CoolingWizard
Silver Product Expert
Silver Product Expert

JoeyLam, 

please do me a favor, start your own thread for your issue, and we will gladly help you. This thread will be closed a soon as it has been resolved for the originator. 

Ken, The AC Cooling Wizard

NestPro and HVAC company owner

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@CoolingWizard, thanks for the help as always!

 

@Treeblanco, thanks for posting. I'm glad to hear that it's working fine now. Let us know if you have other questions and we'd be glad to assist you.

 

@JoeyLam, I'm sorry to hear that you're also experiencing this issue. I'd love to know more about this. How is your Nest Thermostat wired?

 

Thanks,

Edward

JoeyLam
Community Member

Hi @EdwardT please see the post below

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-thinks-I-have-a-heat-pump-No-heat-pump/...

 

I had to hook up an old thermostat just to get the heat going in the house.

 

 

EdwardT
Community Specialist
Community Specialist

Hi JoeyLam,

 

Thanks for the response. I'll be reviewing your thread and respond there.

 

Thanks,

Edward

CoolingWizard
Silver Product Expert
Silver Product Expert

Do us a favor, take a picture of the wires as connected to your old thermostat so we can see how you have it set up because the reason the nest was not working because it was not properly configured when you installed it.

Ken, The AC Cooling Wizard

NestPro and HVAC company owner

EdwardT
Community Specialist
Community Specialist

Hi Treeblanco,

I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hi Treeblanco,

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do.

Thanks,

Edward

Jeran
Community Specialist
Community Specialist

Thank you for helping out on this thread, Edward and CoolingWizard!

Hey there Treeblanco,

I'm just checking up on this thread, do you have any more questions or need any additional help?

Best regards,
Jeran

Jeran
Community Specialist
Community Specialist

Hey there Treeblanco,

Do you have any more questions or need any additional help?

Thank you,
Jeran

EdwardT
Community Specialist
Community Specialist

Hi Treeblanco,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Thanks,

Edward