Have 5 wires with #'s label, 2 green #2&3, 2 red#1&4 and one white #5 wire. Both unit old and new replacement are Honeywell. The newer one ask for 4 wires. The wire got mix up so we were lost and may not connected right. It does not work. What is problem and how can we fix the problem. One red #1 was connected for sure to Y on the old panel and we connected to Y on the new panel. And the white #5was connected to the W to the new panel (not sure if it was connected to the W, it may have been on the C of the old panel) And the 2 green wires we are not sure which # was where. We connect each one to G, It work then was disconnect for the white to be put on White. Thinking at the time that the white wire was C and not needed. What can we do.

Your best bet is to check at the furnace to see if the wires are labeled & to which terminals they are connected. If there are no labels, go to your local home center, buy some 5 wire thermostat wire, run the new wire, & connect to the furnace & stat.