Have a coleman 7900 gas fired heat/cool unit in mobile home. Just installed Honeywell wifi thermostat. I only have 4 wires to t stat. they told me to move the G wire to common on both ends and it will work. Heat works OK but when in cooling mode , compressor comes on but fan does not. The wi fi requires a common wire at the t-stat. If I run a wire (temporarily) from the common side of the 24vac xfmr to the C terminal on the t-stat(and leave the G wire in the G terminal on the stat) everything works fine. Any suggestions without having to do major work and pull in new wires. Honeywell can't helpl