I have a carrier package unit with heat pump. Since I don't use heat pump or furnace can I use a standard thermast?

 

It depends if the carrier system has its reversing valve actuated for cooling or if it is actuated for heating. Not all Mfg's are the same and unfortunately I dont know about carrier. I do know that my Rheem/Rudd has the reversing valve actuated for heating, so in my case, I could run a cool only thermostat, as long as I never wanted heat. I suggest a google search for the setup manual for a heat pump thermostat. These setup manuals normally tell you by Mfg if you need the reversing valve on or off during heating. Hope that helps, sorry for the non answer, answer.

 

No, you’ll need one that powers the O terminal for the reversing valve in cooling.
Or otherwise wire it so the reversing valve is powered in cooling.