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ripdog · Jan 20, 2007, 07:02 PM

The blower on my gas furnace doesn't always start. The thermostat is fine and the blower spins freely. The furnace lights off fine but sometimes the blower doesn't want to start. I should mention it is a direct drive blower. (no belt). Do I need a new motor. Or could it be a faulty switch or relay or something? The furnace is a york mid efficient furnace.

Felrio · Jan 20, 2007, 07:19 PM

Yes, it could be a faulty switch, a relay or something else.

Main Blower motors can brake, but most likely it is something else that it is causing the blower not to work as it should.

Most of the systems the main blower it is activated DIRECTLY by a relay. If that is the case that the relay is faulty, you may need to replace the control board.

Other possible cause might be a limit switch that is open...

I hope this helps...

rickdb1 · Jan 20, 2007, 07:33 PM

Most likely the fan relay is sticking if it works sometimes and not others. Depending on the furnace you have, this could be part of the control board or mounted separately in the furnace compartment.

YorkSucks · Jan 22, 2007, 03:20 PM

Is there a way to test the blower without the relay or other components so it can be sure the blower motor is fine?

Felrio · Jan 22, 2007, 04:37 PM

It's somewhat difficult to say w/o the diagram, but yes there is a way. If it is connected direct but making sure that the connections are right. Also, most of the motors are also activated with a capacitor in series.

RP Capacitors for Motor-Run and General AC Applications
Capacitors

I hope this helps.

labman · Jan 22, 2007, 04:43 PM

You should be able to unplug the blower leads from the circuit board and rig 120 volts to them. Note, you should have at least 3 wires, a white neutral, a high, and low speed lead. There may even be more allowing different speeds. With the neutral connected to a neutral, connect a hot wire to the low speed lead. The blower should start up. Since it is intermittent, try it several times from a standstill. There may be a schematic to help identify the low speed lead. Or you could just check all the leads.

Chances are, as the others said, it is the relay, and you will have to change the board. It would be disgusting to spend hundreds on a new board, and then find out the problem was the blower motor or the flame detector. If the gas goes off again a few seconds after it comes on, likely it is the flame detector. If it stays on a few minutes, likely it is the relay.

ripdog · Jan 22, 2007, 06:58 PM

Originally Posted by ripdog

The blower on my gas furnace doesn't always start. The thermostat is fine and the blower spins freely. The furnace lights off fine but sometimes the blower doesn't want to start. I should mention it is a direct drive blower. (no belt). Do I need a new motor. Or could it be a faulty switch or relay or something? The furnace is a york mid efficient furnace.

Thanks guys, the problem ended up being the blower motor. The bearings were wearing out which did not allow the motor to start every time it was supposed to.