I replaced the blower motor and cap. The motor still won’t start. What else could it be.

I have an old Sears Power Miser 80 Furnace and the fan blower won't turn on when the thermostat is set to "Fan Auto". The furnace ignites, the Fan Limit Control spins around while heating up and when it hits the fan notch, nothing happens. Eventually the furnace will reach the shut off notch and turns off. If the thermostat is set to "Fan ON", the furnace works fine (but of course the fan never will shut off). A little history on the furnace. We just had it inspected this spring by Centerpoint and the tech said it looks OK and it passed all checks. Later in the summer we had an issue with the Central Air and the tech had a difficult time troubleshooting it - was messing with wires inside the furnace and thermostat. Eventually he found the wall thermostat was bad, so he replaced it. The Central Air has been working great since then. But the first time I fired up the furnace today, I have this problem. First Question: Could the Central Air tech have messed up something with the wiring that would cause this furnace fan issue? I've tested the Fan Limit Control with an ohm meter - spun it by hand and when it hits the fan notch, my meter shorts. So looking over things and based on some research I believe the next cause could be the fan Relay? Any ideas ?? Thanks Furnace Info: Sears Kenmore Power Miser 80, model 867.768020