I'm replacing an older Honeywell thermostat with a new programmable Noma/UPM model THM501. There are 4 wires - red, yellow, white and blue. On the Honeywell the blue wire was on the "G" terminal - all worked well. I wired up the new one the same way. However, although the new thermostat shows the heating mode, the A/C comes on and blows cold air - not something desirable with snow on the ground. Can anyone help? Much appreciated,