blower repeats after thermostat is satisfied

when stat calls for heat it runs through a complete cycle then 1min20seconds after the blower stops it kicks on again and runs for another 30 seconds every time. I changed the temperature limit switch to no avail. It still kicks on again each and every time for thirty seconds. After the second blower run it doesn’t kick on again until the stat calls for heat. I vacuumed it all out including the A.C. condenser, still does the same thing. Any suggestions?

What kind of t-stat do you have?