Figure 27 of the install manual.
SPECIAL CONFIGURATION –COMMUNICATING THERMOSTAT AND FURNACE WITH A NONCOMMUNICATING CONDENSER Y1 and Y2 – These terminals may be used to connect directly to a non-communicating condenser when a communicating thermostat is installed to the furnace but a non-communicating condenser is installed in the system. While the optimum configuration is with a communicating condenser connected to the network, there may be installations where this is not desired. In these cases, the thermostat will be communicating with the furnace control and the furnace control will energize the condenser as necessary (the additional relays have been added to the furnace control to allow this operation). The thermostat connections labeled “Y1” and “Y2” on the I.F.C. are normally inputs to the furnace control to turn on the blower when they are energized. However, in this configuration, these (normally) inputs become outputs to energize the condenser when a cooling call has been sent from the communicating thermostat.