Thermostat ON switch does not turn on fan

Is there a wire from the g terminal on the stat to the g terminal on the furnace control board? You need one for the fan on option of the stat to work.

Yes there are 5 wires going from the stat to the furnace control board. W,R,Y,C, and G terminals The stat is a Filtrete 3M-50

Okay. Start at the stat. Jump r to g and see if the blower kicks on. If not, go to the furnace, and jump r to g (make sure blower door safetly switch is pushed in so you have power to the unit). If still no fan, then your fan relay or control board is bad. Let me know what you find.

Jumped r to g on stat,no fan. Jumped r to g on furnace with blower door safetly switch is pushed in, no fan. Fan runs when furnace heat is on.

Now, what wires from the blower motor hook to what terminals on the control board. Also, what brand and how old is the furnace? One step at a time here.

Im about to go eat dinner and relax with my girls, so I may not get back till tomorrow after work. Let me know what you find, and I will do my best to help out.

Furnace is a Lennox G20 series 10 years old. Wires from motor are white=Neutral Brown,Red,and Black=D Yellow=H

All right, here goes. THe A terminal is the cooling speed, the H is heating speed, the CF is the continuous fan (which is the one you want to put the red on). The D terminals are dumby terminals which aren't wired to anything in the board (just a place to put unused wires). So, put your red (low speed) on the CF and you should be all set. You must not have central a/c? Just assuming since nothing is hooked to the cool speed terminal A. If you don't have a/c, you can put the black wire on CF instead of the red and you will get high speed vs low speed. However, I would start with red and see if you are happy with the airflow. Please let me know how things work out.

Placed the red wire on the CF terminal. Fan is on THANK YOU

Glad it worked. Take care