Blower won't stop

[bradcliffe]

The unit is 8yrs old - new filters, unplugged drain pan in blower, cleaned outside unit. The last 3 mornings around 4am (it seems fine any other time!),

we're awakened to a clicking buzzing noise that's coming from the

air handler under the house. Eventually, it comes on but then, it will

cycle on and off with more clicking and buzzing. After a few mornings of that and cleaning now the fan will not shut off. I thought it would be the fan

relay but I replaced that today and it still runs. Tried removing the G wire from thermostat, waited 5 min - still runs. Does this unit have a sequencer and/or circuit board. What do you think the problem is and what's my next step?

Thanks

[Brew Man]

Hey,

At first it sounded like a bad relay clicking,then you said you replaced it and now it runs all the time.you could of connected the wires to the wrong contacts.there are a set of normally closed contacts and a set of normally open contacts on the relay.If you connected to the normally closed set then it will not stop running.If this is not the case,you could still be getting electicity from your transformer.Look at your wiring diagram.

[bradcliffe]

It was already running all the time before I put the new relay on. I made a diagram of the wires on the old one before I pulled them off so, I'm sure I have them on correctly. So, you think the transformer would be the most likely culprit? Is there a way to test it to determine if it is bad?

Thanks

[Brew Man]

Hey,

Like I said, you need to look at your wiring diagram to see how it is wired.You trans former could be fine.Your transformer receives a certain amount of electricity(say 220 V) and it steps this down to let's say (24 Volts)If it's doing what it's suppose to be doing then it is fine.

[Rrey199]

 Hi. Try disconnecting all the t-stat wires from the control board in the bottom of the furnace. If the fan still stays on, you either have an open limit switch or a bad control board.

 

[RawNerve]

It sounds like the thermostat wiring may have a short in it. disconnect at furnace board and see what you have.  Sometimes small furry critters will chew on the wiring and sometimes the weedwacker will hit it.