I have Gas heat/AC unit. I just installed HoneyWell RTH6300B thermostat. I have four wires from my old thermostat(G, W, Y, R). On new honeywell it has fith connection Rc. I connected all wires as instructed and jumpered R to Rc. Both gas heat and AC working however Fan only coming on for AC not for heat. Currently Fan setting is "Auto" How can I fix this fan issue for gas heat. By the way my Unit is York M NO: G/VA036SA. I matched wires on Unit to thermostat. Please help how to fix fan issue for gas heat.

Here is the first thing I would do. I would reset the thermostat to it's default settings. Here is how to do it:

1. Press Set Clock/Day/Schedule

2. Press Set Schedule

3. Hold Done and Next down at together for about 5 seconds.

Now leave all the settings alone. Make sure the thermostat is set to Heat and that fan is on Auto. Turn the heat up so that it kicks on and see if the fan responds.

Aaron