Lennox G14 fan limit switch question

I have a Lennox G14 furnace that likes to turn on for about 15 - 30 seconds only, and then shut off. Otherwise it runs like normal, but will do this '15 second' thing almost always after the room has reached it's desired temperature.
I was told to check the fan limit switch. Where is this switch? What do I look for? Are there adjustments that can be made on it?
Thanks.
Clark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sounds like the switch in your thermostat.

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.