Wiring Connections - Not working with Heat Pump

[cvergin]

I have a Honeywell T6 Pro thermostat that I am trying to replace with the Nest Learning Thermostat. I have a heat pump. There are 5 wires connected in the current thermostat - Y (yellow), G (green), C (blue), W (white), and R (red). When I connected to the Nest, I connected Y to Y1, G to G, W to W1, C to C, R to Rc. When I tried to run the system, the heat turned on instead of the AC (it's 110 in AZ, so heat is certainly not the goal). I tried putting the R wire in the Rh position. Same problem. From everything I can read in the help community, a heat pump usually has a O/B wire. All the suggestions are to switch the settings for O to B or B to O. I do not have that O/B wire, but the current Honeywell thermostat works just fine with the heat pump. Any suggestions of what else could fix this problem?

[CoolingWizard]

@cvergin if you have a heat pump, you must have a wire attached to what is known as the O/B terminal on your T6 Pro thermostat. On the Nest thermostat it is combined as O/B*. This OB wire is what changes the heat pump from heating to cooling (O models) or from cooling to Heating (B Models).  Please upload  the picture you took of the old thermostat wiring before you disconnected any wires. The T6 Pro OB terminal is on the right side near the top of the base just above AUX terminal. 

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AC Cooling Wizard

[cvergin]

Before - there is no O/B wireMy installation of Nest

As I said in my original posting, there was no O/B wire in the original wiring. 

[CoolingWizard · Accepted solution]

@cvergin You cannot have a heat pump without OB wire to change the system mode.  Can you get me a picture of the outdoor unit manufacturer label showing me the model number please?

AC Cooling Wizard