Forced air furnace unit not blowing heat.

[pjdudley]

Make and model not known (nor do I see it printed anywhere on heater)

I have a forced air furnace with cooling unit
outside. When I switch it on for heat it would
normally start out making a humming sound for
awhile, then it would sound like it was lit and
blowing flames, and after some heat built up the
blower would come on and heat the house until
the temp setting on the thermostat was reached.
But lately I turn the switch on, I get the humming
and sometimes the flame sound, but not always.
But the blower never comes on. Sometimes
when I would switch back and forth between off
and on the blower does come on, usually for one
cycle only.

I had a similar problem in the summer with the
air condition part of the unit. I would here
humming but blower does not come on. Play
around with the switch, blower might or might not
come on. Finally it began to work correctly and
lasted out the summer.

Anybody have any idea where to begin tracing
the problem ?

advTHANKSance

Paul

[LazyPup]

sounds like the fan relay may be sticking.

[imeduc]

If you turn it to fan on at the tstat and the blower dont come on right away Id check the blower motor and capacitor also.

ED

My mistakes dont define me they inform me.

[pjdudley]

Thanks for the reply(s).

I've noticed something else. I've used the circuit breaker box
to power the unit off and on. The unit worked ok for awhile,
sending nice warm air into the house for some time, although
it stopped before it should ( I have the tstat set for 70,
it would get up to around 60ish before quitting ) and then all
I hear is humming, at which time I kill the c'breaker. Try
again right away and only humming. Wait a couple hours and try
and get warm again, but same as above...

Paul

[imeduc]

Check the blower motor out

ED

My mistakes dont define me they inform me.

[pjdudley]

> Check the blower motor out
>
>ED

Ed, could you please elaborate a bit. Not sure what I should look
for. I just now came in after 5 hours away. I had left the c'breaker
of. I just now flipped it on and it seems to work fine - but I know
it will cut off at some point and sit there softly humming, at which
time I kill it at the breaker box.

Please tell me more, so I'll know what to look for tomorrow at
day light.

Paul