Air conditioning thermostat wiring help
I am guessing B is common in your case. In that case Y and B. 


I have drawn a line though the terminsals you will not be using since you have straight cooling and are using the air handler like an electric furnace.  R goes from the thermostat to the air handler but not the condensing unit as does W1 which is your heat strip. O is not used since you do not have a reversing valve. Y goes from the thermostat to the air handler then carries on to the condensing unit.  Note the common 24 volt is labeled B or B/C (this is typical with Trane products).  The B is likely labeled C on your wifi thermostat.  So C from the thermostat goes to B on the air handler and then on to the condensing unit. It does not matter which wire from the condensing unit goes to B or Y. I hope this edit clears up any confusion.