furnace blower sticks on

I have a York Stellar furnace that is 16 years old. After the heat
cycles on and off, the blower will occassionally stay running. If I
tap the fan/limit control very lightly the metal disk unsticks,
jiggles a bit, and then the blower shuts off. Then it may work fine
for a few cycles, but sooner or later it will stick on again and need
to be tapped. I assume that this is the part that needs to be
repaired, but is it pretty easy? The fan/limit control is a
Honeywell, so I assume I can find the model/part# and get a
replacement or just take the old one in. I've attached a pic at
http://img199.imageshack.us/img199/2626/img1509fo.jpg

Thanks!

On Thu, 5 Nov 2009 17:40:13 -0800 (PST), Matt <[Only registered and activated users can see links. ]>
wrote:


You should be able to find a tapper at a reasonable charge. The Home
Depot parking lot is a good place to look, or Craigs list whereever au
peres are listed. When the burner is on and the blower should be
running, since he's in the basement, he can do laundry or something.


Should the lower limit switch really be set at 50? Or is that for AC
too? (I don't have a control like that, for some reason.)

I don't see the metal disk, but it seems if it sticks, one needs to
find where it sticks and either bend whatever it touches away from it,
or file down the disk a little at that point. But I have no idea how
your gizmo work or what I'm talking about. Except that filing seems
preferable to buying another one.

On Nov 5, 8:15*pm, mm <[Only registered and activated users can see links. ]> wrote:

The contacts will spark from breaking the curent when the contact
opens as the temperature in the plenum gets cooler. The sparking
roughs up the surface causing little pits and valleys. Eventually the
pits stick in the valleys and the contact does not open. If you can
get near them, a women's emery stick for filing nails can be used to
smooth the surface and keep the switch working for several months. I
have to use an emery board on our 50 year-old gas furnace about every
2 years when the blower does not shut off after the air has cooled
(when on the Heat setting).

On Thu, 5 Nov 2009 22:15:12 -0800 (PST), "hr(bob) [Only registered and activated users can see links. ]"
<[Only registered and activated users can see links. ]> wrote:


Very interesting.


I thought emery sticks had sand on them that embedded in the contacts
and made them wear again faster than they would if filed with an all
metal file. At least that's what I recall from instructions on filing
contact points on auto distributor points and/or voltage regulators.

Wouldn't a metal file, like a point file (which is thin and fits
between contact points, be better, last longer.


How come no one's nagging you to get a new furnace when they used to
give me a hard time here for having a now-30-year-old oil furnace?

On Nov 5, 8:40*pm, Matt <[Only registered and activated users can see links. ]> wrote:

Hard to tell from the pics, but is your low limit set on 50? That
should be bumped up a little bit. Otherwise you are blowing 50 degree
air in your house. Maybe that is your problem, because the fan will
not shut off until the plenum cools off to 50 degrees. Try 75 degrees.

On Nov 6, 1:15*am, "hr(bob) [Only registered and activated users can see links. ]" <[Only registered and activated users can see links. ]>
wrote:

Thanks for the advice Bob. Where are the contacts? Do I likely have
to take the fan/limit control off the furnace or take the whole thing
apart? No problem doing that, I just want to know what I'm looking
for.

Thanks

"Matt" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...

You may not be able to get the exact part but a universal replacement part
can be purchased.

First I would move the low limit up to about 80 or 90 degrees like another
poster suggested.


Colbyt

"Matt" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...

I'm with some of the other posters here... I think the control is misadjusted. That little metal
tab sticking out near the "50" marking controls when the fan turns on and off, and can be moved. 50
is way too low a setting, it should be closer to 100. The "Off On" markings under the word "Fan"
indicate the range where that is supposed to be.

Eric Law

On Thu, 5 Nov 2009 17:40:13 -0800 (PST), Matt
<[Only registered and activated users can see links. ]>wrote:



Just replace it.

Okay, sorry I should have clarified before. I took the pic at a point
where I was experimenting with the adjustments. The metal tabs are
usually set around 130 (high) and 80 (low). I had pushed the lower
one down to 50 so that I could slowly move it up and see at which
point the blower shut off. The problem is that when it does stick, it
requires only the slightest touch to un-stick - so it's impossible to
hold the dial and move the tab without manually "unsticking" it. The
issue is definitely not the setting, since when I have it set on 80,
the blower continues to run until I manually unstick it - at one point
i was out of town and my wife said it ran for 2 days straight, and
upon coming home and measuring the temp of the air in the plenum, it
was much lower than 80.

So really I either need to replace it or file the contacts. I'd like
to try the filing, but can anyone tell me where the contacts are? If
I do need to replace it, can anyone tell me if it's a straighforward
replacement job?

Thanks