No separate w and y

[SDCarson]

Hello,

I am trying to wire my Nest Learning Thermostat.

I have a separate furnace and ac unit and the old thermostat was wired with only 4 wires.

a jumpered wire between W and Y, a C, and a R.

Do I still need a jumper between W and Y? I tried wiring to just W and it seems to turn on heat and ac. Is it possible there’s another jumper somewhere down the line where the old furnace and newer ac unit are connected?

[Jeff]

Hi, everyone. 
In an effort to keep content fresh on the forums here and prioritize current issues, I'm going to go ahead and close up this thread. If you have any outstanding issues from this post or any other problems, please feel free to open up a new discussion.
Thanks,
- Jeff