Nest E Y1 cable cutting power to thermostat
You will need a wire going from the C on the thermostat to the C on the furnace, 5 wires total. R to R, W to W, Y to Y, G to G and C to C.  At the furnace there will also be a second wire on the Y and C and they will go to your condensing unit.  I can not tell from your pictures but it looks like the blue wire on the furnace C is probably going to the condensing unit.