Constant blower

Unit is BDP (Carrier) model 394GAW060125 furnace and when I raised thermostat, the blower immediately came on and continued to run without delay for heat exchanger to heat up. Can it be thermostat problem or deeper?

No help for you yet so I will take a shot in the dark is this a new install first time for the furnace use. If so most of the newer units have DIP switches on the control panel that have to be set for proper operation. If it is not a new install yes it could be as simple as a stat problem but most likely would be in the control board itself.

Thanks, this is my own unit and want to try with replacing the furnace control circuit board first because stat worked fine when switched to a/c.

Charley…how about a defective (shorted) Klixon? Unusual but not impossible, right?

Mike I doubt it not going to be a standard Klixon that brings the blower on and or off on a newer furnace

I have a relatively new York furnace that does that. The blower kicks on to ensure that there is a proper draft prior to ignition (not sure how that works). If the blower fails for some reason, then the gas won’t kick on and ignite. I was “educated” by my HVAC tech when he installed it, and warned about that ahead of time. It’s a little bit annoying because when it kicks on, it does blow cold air until the burner starts. But hey…what is, is. And if it is somehow safer, then so be it.

like Charley says its more than likley the control board ,the blower is controled by the board .

New control systems bring on blower and/or combustion fan blower for 45-90 seconds to clear any conbustible gases from unit prior to firing burners

That sounds familiar. :slight_smile:

When you say the blower comes on almost immediately, do you mean the induced draft blower or the air handler blower. The induced draft blower comes on almost immediately to clear fumes. The air handler blower doesn’t normally come on till the H/E warms up.

The blower in question is the air handler but after spraying the circuit board with an electrical contact cleaner. The unit is now functioning as it should. I guess that the contacts that were not in use for over 6 months had a residue that prevented the furnace sequence from working properly. Thanks to all for the input.

Louis Change your filter more often don’t let your board lint over cleanlyness is next to Godlyness:p:D have a good one.

If it is an electronic thermostat some have a set up switch for gas or electric furnace. The switch or programming may be set for electric. In this mode the main blower will come on immediately.

Unit is short cycling now. I’m starting to believe that control board needs replacement. Thats probably what the HVAC tech will suggest.

What are the fan “on-off” settings? Standard setting are usually “on” at 150F and “off” at 120F. Some furnaces I see have them set at 120/90 for energy savings purposes. In many instances, this will cause the blower to short cycle at the end of the heating cycle.

Many inspectors are weak in the HVAC area. Myself included.

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