Trying to go from a four wire cooling/heating unit to a Honeywell
RTH7000 series. I cannot get the cooling unit to go on, everything is
hot air. I have the following wires:

Y
Rc
G
O

On my old unit the Y was attached to both the Y and W. Does this mean
I have to run some kind of jumper between the Y and W in the Honeywell
thermostat? Can anyone help?