Gas and Oil Home Heating Furnaces - Blower does not come on

I have a Rheem gas furnace with electric ignition, about 19 years old. Pilot and burners work fine but go out after about a minute. I've replaced the fan and limit switch on advice of the gas company. Also tested fan by running power form the main furnace to fan in second furnace. (I have a similar Rheem heating the downstairs that sits next to the main furnace.) Still no blower. Any ideas?

-Joe

Check for power at the blower motor??? Capacitor good??? Motor bad or good ????

The gas man checked for power and I'm guessing that the motor and capacitor are OK because of my substitution test. Could there be anything else? I'm pretty sure I can handle a replacement but am weak on the diagnosis and checkbook.
-Joe

So the blower fan does work?, when you did that jumper or substitution test run?, but just does not come on automatically in your furnace when it should?

If that is the case, I guess you have to follow back the wiring through the fan/limit and on back from there.

Do you have a furnace where either the fan/limit switch has a shaft that can be pulled out or pushed in to let the blower fan run all the time?, or a setting on the thermostat that allows you to set the blower fan to "on", rather than "auto"? If you have either of these, at least til you resolve the issue, you can at least get heat to blow, by manually turning on the blower.

Thanks for the tips. In this case it was a burned out relay. Pretty easy to detect by detaching.

-Joe