Furnace fan won't run in the "on" position

[Softballdad]

Hoping someone here can help me out.

Bought a house 2 years ago, built in 2004. It has a Trane XB80 (2004) furnace that has been causing me problems since we moved in.

In the past year I've had to install a cage to stop the furnace from sucking in the filters. The cage has worked (after destroying a motor first) but the filters do seem to get clogged up quickly.

I've also put in a motherboard a year ago.

Current problem:

The fan will kick on when the furnace is heating, but the fan will not stay on when the furnace isn't heating. I know I tested the motherboard after installing it and all functionality was there. I could run the fan in "on" mode, or run my A/C & Furnace in "Auto" - everything was fine.

I do have concerns about humidity in the room. Not significant, but was wondering if this were the proverbial "ghost" in the machine.

Any help would be appreciated. Thanks - Scott

[paul52446m]

Hoping someone here can help me out.

Bought a house 2 years ago, built in 2004. It has a Trane XB80 (2004) furnace that has been causing me problems since we moved in.

In the past year I've had to install a cage to stop the furnace from sucking in the filters. The cage has worked (after destroying a motor first) but the filters do seem to get clogged up quickly.

I've also put in a motherboard a year ago.

Current problem:

The fan will kick on when the furnace is heating, but the fan will not stay on when the furnace isn't heating. I know I tested the motherboard after installing it and all functionality was there. I could run the fan in "on" mode, or run my A/C & Furnace in "Auto" - everything was fine.

I do have concerns about humidity in the room. Not significant, but was wondering if this were the proverbial "ghost" in the machine.

Any help would be appreciated. Thanks - Scott

On your furnace board jump between R ans G and see if the fan comes on,
if it does the problem is in low volt wiring or the stat. Take the stat off and jump the r to g wires if the fan runs than wires are good, problem is is the stat. At stat you do have a wire to the g post and same wire to g post on the board? Let me know what you find out. Paul

[Softballdad]

Thanks. We're busy with softball all day today but I'll give that a try tomorrow and let you know. I appreciate the help.

[brettyg]

The thermostat needs to have four wires going to it in order to have the fan come on by itself. The four colors of wire should be green, white, red, and yellow/blue. The green wire needs to be on the g terminal of the thermostat and moin circuit board. If no green wire runa a 18g wire to thermostat from furnace.

Hope this helps,
Chicago Heating And Air Conditioning Repair Service

[paul52446m]

The thermostat needs to have four wires going to it in order to have the fan come on by itself. The four colors of wire should be green, white, red, and yellow/blue. The green wire needs to be on the g terminal of the thermostat and moin circuit board. If no green wire runa a 18g wire to thermostat from furnace.

If you read he post you will see that he says after he changed the board the fan
ran in the on switch, and also the fan ran with the air con. Must be a fan wire there. Paul

[brettyg]

Your right i misread the post. I thought he was saying he tested at the board with functionality. Man im just trying to help out where I can . Your a real B buster