American Standard - Furnace Heats then Fan/Blower Runs and Won't Shut off

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  #1  
Old 01-26-12, 02:59 AM
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Post American Standard - Furnace Heats then Fan/Blower Runs and Won't Shut off

American Standard Upflow/Horizontal Gas Furnace with Fan Assisted Combustible System, UE060936

Problem just started. Heats fine but instead of shutting off the fan/blower continues. Won't turn off at thermostat when switching from heat to "off".

Happened once Sat morning. Happened twice yesterday and now seems to keep happening every time heat cycles on (after I've been able to get it turned off).

Checked and changed air filter. Was dirty and probably the cause of what's happening now. Changed batteries in thermostat but seems unrelated.

Have been researching this online but can't find anyone who says they can't turn it off at the thermostat.

What I've done inside is turn off at thermostat (though fan keeps running), then back on. Hear the clicks. Bump temp to just above room temp to hear the click. Usually it turns off in a little while then I can turn it "off" and it stays off. If I don't turn it off when it finally shuts off, then within minutes it will kicked on, heat just fine and risk the fan/blower running continuously again.

Ready to go up to the furnace in the attic now to address it there. Manuals are limited for a novice. Wondering if I can turn the furnace off and on up there - would help to limp through this a little while. Breaker is outside and not an option at night.

Anyone else have this problem of fan/blower not shutting off when heat if turned off at thermostat? Does it sound like limit switch to check or replace as next process of elimination? Elementary guidance appreciated.

Not sure if it matters but I'm female, on a limited budget and prefer to take care of this myself if possible. Thank you.
 
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Old 01-26-12, 05:07 AM
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running

depending on the age of the furnace,the fan/limit control could be bad.or the main board that controls the fan. you have to look at the wiring diagram on the inside ppanel to see what controls the fan.
 
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Old 01-26-12, 05:10 AM
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runnig

it could be a limit switch,but if it lights again,it is probably not the limit.you could check them on the wiring diagram,and try and locate them. some have a small button ion the center you push to reset.
 
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Old 01-26-12, 08:23 AM
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could be a sticky relay on board, then you need a new board. You're sure the fan is at auto, not on position at tstat.
 
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Old 01-26-12, 10:04 AM
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Yes, sure thermostat settings are Heat/Auto - NOT "on" and fan/blower doesn't shut off when turned from heat to "off"

What do you mean if it lights again probably not the limit? If "what" lights again?

thank you
 
 

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