Randy,

In your case perhaps the centrifugal switch is doing it's job? Could be a sign of something plugging the airways, a problem with the chimney or perhaps even a cracked heat exchanger. Clean and check everything.

Also be sure your blower wheel is tight on the booster motor.

Mark

If some of your heating elements are coming on but not the blower, then most likely the culprit is the sequencer because the M1 & M2 poles are what turn on the blower motor and 1 heating element. But if you are only getting 21 volts to the bottom of the sequencer, that could be an issue too as y...

Sounds like a defective board.

Mark

Tell us what you have checked or tried. Thermostat ok? Getting power to the unit OK? Breakers OK? If all that checks out, then need to check power coming from the transformer, also check sequencers.

Mark

You could always clean the flame sensor with a bit of steel wool. But if it's not even lighting, then check and see if you are getting power to the gas valve during that period of the start-up. If you are getting power, perhaps the gas valve isn't opening and you need a new valve. If you aren't gett...

Sounds to me like the booster relay is sticking. Part number 7975-3771. http://www.aberdeenhomerepair.com/store ... -24V-relay

Mark

Hi,

If you're unit has a switch that allows you to turn to 'fan', then you're all set. You can then use this thermostat to turn on the blower in timed intervals to move air. http://www.aberdeenhomerepair.com/store ... lower-ctrl

Mark

Sounds like the fan switch is the likely culprit. Part number 7975-3281 which you can see here: http://www.aberdeenhomerepair.com/store ... -7975-3281

Mark

When the fan is doing the on-off stuff, put a meter across your limit switches and see if they are opening and closing at the same time.

Mark

You possibly have a limit switch tripping prematurely. Or excess heat is building up inside the furnace due to possible factors like the motor no longer spinning fast enough, or clogged filters.

Mark

If the blower motor is too big or too small, it will wear out prematurely.

Mark

The sequencer is kind of the brains of your unit. Be sure it's getting a strong 24-26 volts to the bottom of it. The top switches should close letting 240V of power to the motor and elements. If not, you need a 3110-3571 sequencer which can be seen here: http://www.aberdeenhomerepair.com/store/produ...

Are you getting a strong 24-26 volts to the bottom terminals of the contactor? Any less and it won't hold the contactor closed.

Mark

Possibly sounds like issues with the control board. Maybe a relay or something sticking on it.

Mark

The burner would not light nor the fan would not come up normally?