Furnace blower will not shut off

I have an old singer gas furnace. The blower will not shut off. Put in new relay and new thermostat and still stays on. Please help
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, January 16, 2015 at 12:44:06 AM UTC-5, Wes wrote:

ahh any chancesomeone set the thermostat to fan always on
any chance someone set the thermostat to fan always on?
some friends called me our furnace is running forever......
I went over and moved the switch
?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, January 16, 2015 at 7:41:55 AM UTC-5, bob haller wrote:

+1
And if that's not it, next I'd find and disconnect the thermostat fan wire at the furnace. Eliminates the possibility that it's a bad thermostat, short in the wires to the thermostat, etc.
Next would be that it's a bad control board. Don't know how old that furnace is, what technology it uses, etc.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Wes wrote:

Hi, Sounds like you have error situation like high limit sensor triggered. Did you turn the furnace off/on? Did the blower stop?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
alt.home.repair:

I just last week went through this exercise for the same symptom, the blower ran constantly. I had hoped it was DIY fix, but these newfangled furnaces are extensively computer controlled, and there are few easy- and-cheap-to-replace parts like relays. It turned out that the furnace's motherboard had partially failed and had to be replaced. It's working fine now.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.