On Nov 6, 8:16*am, DerbyDad03 wrote:
On Nov 6, 8:18*am, Matt wrote:





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

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

Do you have a humidifier attached to the furnace?

My old furnace had a humidifer and the probe-type fan limit switch
described in this thread.

When I had a problem with my blower staying on/not coming on, I pulled
the fan-limit probe and found it coated in mineral deposits - that
white flakey stuff.

I replaced the limit switch and yanked the humidifier and all was well.- Hide quoted text -

- Show quoted text -

When I described filing the contacts, I should have said replacing the
limit switch was a good option if you can get a replacement with
similar mounting holes and probe size. The humidifier dust collecting
is logical, altho I have never heard of it being a problem before.