Author Topic: Gas furnace blower motor always on  (Read 1725 times)

Offline marquesjw

  • ***
  • Posts: 1
Gas furnace blower motor always on
« on: December 11, 2015, 11:56:30 PM »


so i recently purchased a home with a 80% gas furnace. now the fan is always on, heating or not. so i took a look at the control panel and ive got a jumper wire between the two terminals

can i just remove it and hook up the green wire that goes to my thermostat? im trying to get it so its low fan speed when not heating and medium or full speed when heating

thank you

Offline Admin

  • Administrator
  • *****
  • Posts: 2334
    • HVAC TECH GROUP
Re: Gas furnace blower motor always on
« Reply #1 on: December 12, 2015, 01:24:34 AM »
Yes, remove the green jumper wire between R and G to stop the fan.  You can connect the green wire from the thermostat wiring to G on the thermostat and furnace board.

When you turn the thermostat fan to ON it will energize the heating speed.  It looks like the low speed red wire is connected to the HEAT terminal, so your furnace has been running on low speed continuously.

It looks like the high speed black wire is on COOL, but it doesn't look like you have air conditioning.

You can unpark the medium speed blue wire and connect it to HEAT, and move the low speed red wire to CONT, which is beside the COOL terminal.

Now when the furnace heats the fan will run at medium speed and if the thermostat fan switch is turned ON, the low speed fan will run continuously when the heating cycle is complete.

Offline Sergroum

  • Pro Techâ„¢
  • *****
  • Posts: 121
Re: Gas furnace blower motor always on
« Reply #2 on: December 16, 2015, 10:39:00 PM »
Barring a severe case of ignorance, or insanity, there might've been a reason why this jumper was placed there. Clearly you have the wires for it. There could be a possibility that "Fan ON" option on the thermostat is faulty and that was the solution the previous home owner arrived to? Unlikely. Very. But just be open to possibilities of someone purposefully doing this for some weird reason.