Only 5 T-Stat wires to my Heat Pump T-Stat

[KruegerSC]

@CoolingWizard, please help.  When installing my 1.5 ton heat pump system, the contractor only installed a (5) wire tstat cable.  

I have Y, C, W, G, & R connected at nest. (No O/B)

The contractor jumped out Yellow and Orange in handler unit

Cooling is working

Heating is only using electric heat strips.  The outdoor unit is not being called for in heating mode.  Is there anything I can do or do I need to pull a 6 conductor T-stat cable?

Thank you in advance for any insight!

[CoolingWizard]

@KruegerSC , first of all, allow me to apologize to not responding quick enough for you. I’ve been very busy. It’s very important that you use the heat pump for heat as well because electric heat strips are extremely expensive to use. You will need a thermostat cable that has at least six conductors. I would recommend you install a replacement cable that has at least seven conductors inside. Here is why I suggest seven conductors for Heat Pumps:

R - 24V Power from Air Handler

Y - Compressor Relay

W2/Aux - Auxiliary Heat

OB - Heat Pump Reversing Valve

G - Blower Fan Relay

C - 24V Power Common

E - Emergency Heat 

The AC Cooling Wizard