A common problem is this situation is the thermostat itself, though it also depends on the make and model. A proper 'diagnosis' would be found by a professional, especially if it's been awhile since the unit has been serviced.
No it is not advisable. Put it on AUTO. The furnace will decide when it is practical to turn the fan on. Really. No it is not advisable. Put it on AUTO. The furnace will decide when it is practical to turn the fan on. Really.
The usual cause is a failed blower resistor, also called a blower power module on a auto temp system.
The blower motor speed resistor is burned out. The resistor is located close to the blower motor and is easy to change. Your local auto parts store will have that part for you.
number of things can cause turn tstat from auto to on to rule out power to unit, transfomer and motor if it dosent u have voltage problem or bad capacitor or fan motor You may want to try askarepairtech.com. They can diagnose the problem by phone and if you are handy, you can replace the part yourself. If not, they can do it.
The blower motor speed resistor is burned out. The resistor is usually found close to the blower motor. Auto parts stores carry that part and it is easy to replace.
Blower motor might be good. Check fuse(s) in fuseblock first. Check also the blower speed switch and the blower resistor. A service manual will be indispensable. Auto parts stores sell inexpensive, but usable, versions.
It should be called the auto HVAC blower motor resistor wire harness. Goes from the auto climate blower motor resistor to the blower motor.
On the auto temp unit it is called a blower power module.
warning: flame roll out can cause serious injury 1) turn service switch off at the furnace 2) adjust thermostat so set point is 5-6 degrees above room temp, set t-stat for heat, and set fan to auto 3) remove ignition compartment door of the furnace as opposed to the door enclosing the indoor blower motor 4) turn the furnace service switch back on 5) do not look directly at the combustion burners as flame will shoot out of the burner compartment 6) observe the ignition finally proper ignition is confined to the area intended for combustion, with a blue flame. a roll out will cause the flame to ignite beyond the burners and may even blow beyond the blower compartment. further, a roll out can persist beyond the initial ignition sequence.
I have the same issue - I have found that if I wiggle the wires at the blower motor - the blower kicks in. I haven't gotten to it yet but I suspect that the plug connector is dirty inside or doesn't have enough pressure to make good contact. I plan on cleaning the connector and maybe bending the contact to create more pressure. As might be suspected, it only fails when it is very cold outside and you really need the blower. i had the same problem, replaced the blower motor, $45, advanced auto parts, works good now! I was having the same problem. My husband found a loose connection under the hood on the blower fan. I also had the same problem. I fount that the cause was a defective wire to the blower control module
Hard to say. It may cause no damage at all and then again it might cause serious problems.
On an auto temp system the blower motor resistor has failed and needs replaced.