Gas and Oil Home Heating Furnaces - Day & Night furnace???

Hi everyone!!I'm having a problem w/ an old day & night furnace(probably 33 yrs. old.)The fan doesn't seem to want to shut off.We were out yesterday and replaced a wire from the limit to the thermostat and everything seemed fine.Today the fan won't stop running.Changed the t-stat and replaced the fan limit.Fan still runs.Also,I have to admit I'm not to familiar w/fan limits.How do they operate and what should they be set to????PLEASE HELP!!!Thanks.

We were out yesterday and replaced a wire from the limit to the thermostat and everything seemed fine.?????
Dont know what you did here.

replaced the fan limit.Fan still runs.Also,I have to admit I'm not to familiar w/fan limits.How do they operate . From the heat in the furnace
The control should be set for fan on about 110 -115 and off about 95. All furnace are different. You want the fan to come on as soon as it can and off so it dont blow cool air. Now lots of time in old furnace like this.if its sill warm outside and the pilot is on it can turn the fan on from the heat of it,

ED ;)

Thanks for the quick response Ed!!

We replaced the wire from the thermostat to the limit .The old wire was very worn and bare.The wire(black) runs from the limit to the yellow wire where it is tied together.

It is about 50 degrees outside.

Furnace seems to fire up ok, it just seems to run too long.

How long it runs is all in the heat loss of the home. But it is better to run longer than on and off on and off.
Still dont know why the wire goes form the tstat to the limit there?