All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.

wrote:
All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.

sounds like a stuck relay on the control board, try powering it down,
tapping on all the relays, and powering back up.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

wrote in message
...
All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.

It could have a relay with a slightly welded contact. Tapping on the furnace or
the relay itself could jar it loose.

wrote in message
...
All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.

Could be a sticking relay, could be a bad thermostat from the heat
exchanger. Try turning off all power to the heater and then turn it back on
and see if the blower stops when power is restored.

On Dec 6, 12:49*pm, wrote:
All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.

First off, disconnect all the wires at the T-stat and see if it shuts
off. If it does, you have a faulty t-stat/wiring.
If it stays on, put the wiring back for the T-stat, and now disconnect
the T-stat wiring at the furnace board to confirm its not the wire
shorted in the walls someplace.
If it still stays on, it could be a stuck relay on the control board
on the furnace. You can try tapping it.
Another possibility is that if the chamber/duct temp sensor could be
faulty, giving a high reading and could be telling the blower to stay
on.

Thanks everyone!! I appreciate the prompt replies.
I powered it down, tapped on everything and it works fine now.
Ed S.

Mikepier wrote:
On Dec 6, 12:49 pm, wrote:

All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.


First off, disconnect all the wires at the T-stat and see if it shuts
off. If it does, you have a faulty t-stat/wiring.
If it stays on, put the wiring back for the T-stat, and now disconnect
the T-stat wiring at the furnace board to confirm its not the wire
shorted in the walls someplace.
If it still stays on, it could be a stuck relay on the control board
on the furnace. You can try tapping it.

Things that go away by themselves when tapped usually come back by
themselves shortly thereafter. G

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

Another possibility is that if the chamber/duct temp sensor could be
faulty, giving a high reading and could be telling the blower to stay
on.

wrote:
Thanks everyone!! I appreciate the prompt replies.
I powered it down, tapped on everything and it works fine now.
Ed S.

Good to hear it. However, as I'm sure you know, things that are "fixed"
by percussive diagnostics don't always stay fixed, so you may wish to
find which relay it is that controls the fan and purchase a replacement.
It's likely soldered onto the board so try Digi-Key or a *good*
electronics supply.

The contacts may have welded due to excessive current draw by the fan
motor, in which case a replacement relay may only last a year or two
before failing again. You may want to check it with an ammeter against
the rating on the label, and replace the blower if indicated.

Of course, this is best done in the spring, when you're not using heat
or A/C

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Just power down, and tap on it three times a day for the rest of your life.
Very simple.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


wrote in message
...
Thanks everyone!! I appreciate the prompt replies.
I powered it down, tapped on everything and it works fine now.
Ed S.

wrote:
All of a sudden my furnace blower runs constantly even though it is
set on "auto" at the thermostat. The heat cycles on and off properly
(fortunately because it is 19 degrees outside). The furnace is about
10 years old and is gas. I seem to recall there is a wiring option on
the motor for it to run constantly but no one has messed with that
since it was installed. I would appreciate any ideas on what the
problem might be.
Hi,
First unhook wire on G terminal on your 'stat. If it stops problem is in
the ;stst. If not problem is in the furnace, control board of replay
depending on how old the furnace is.

You are fortunate that the unit continued to function. There are
several brands that go to continuous fan run to tell you that
something needs attention. Most recent units have an electronic
control board. There should be a standard "flash" chart on the
inside of the blower cover that has the wiring diagram. Count the
number of flashes on the board - the chart would tell you what to
trouble shoot. There is a daisy chain of safety relays usually
with the same color wire looping them together. There is a small
reset button on each of these. There is also a limit switch on
the burner box and a switch if the power venter doesn't come on.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




wrote in message
...
All of a sudden my furnace blower runs constantly even though it
is
set on "auto" at the thermostat. The heat cycles on and off
properly
(fortunately because it is 19 degrees outside). The furnace is
about
10 years old and is gas. I seem to recall there is a wiring
option on
the motor for it to run constantly but no one has messed with
that
since it was installed. I would appreciate any ideas on what the
problem might be.

responding to
http://www.homeownershub.com/mainten...ff-346492-.htm
moshei wrote:

This gem is located behind the front decorate cover. Remove it and look
for a metal box attached to the furnace. It will have a cover on it and
the cover will be held in place by two screws.





-------------------------------------
TeleTemp Cooling & Heating

responding to
http://www.homeownershub.com/mainten...ff-346492-.htm
moshei wrote:
The gem located behind the front decorate cover. Remove it and look for a
metal box attached to the furnace. It will have a cover on it and the
cover will be held in tow place by the screws.



-------------------------------------
TeleTemp Cooling & Heating