House fan low speed

[pascal]

Hello,
I have a old carrier furnace Model 58SE100-2 series 214.
I like to leave the "house fan" on, all the time so it can filter the air of the house all day/night. How do I set up the furnace blower speed so I can keep the lowest speed when it is on all the time and then the speed change when the thermostat calls for heat/cold
The motor has three speed low-medium-high. I do have a picture of the circuit board if that can help but i don't know how to post it on here.
Can anyone help me with this issue please

Thanks

[how]

Is only one speed tap connected to anything. Do you have a thermostat with a fan on switch and is that fan speed the same as the heating * Are the other motor wires hanging marreted off or are the connected to the * In park positions or *

[Freon]

FAN-ON setting at the thermostat usually uses the AC (cooling) blower circuit. So you need to have the lowest speed (possibly the red motor wire) placed on the AC/Cool lug of the fan control.

BUT... make sure you tape the wire you remove or put it on the PARK lug and label it as AC. In the summer you will need to swap wires again or your indoor evaporator coil may become a block of ice due to too little air flow.