Furnace Blower Motor Control ...

[casturbo]

I'd make sure the exact type and length of fan control was installed on the furnace when it was replaced. These controls are critical to heat exchanger longevity. Just a minor adjustment to these controls can wreak havoc on x-changer temperature.

[htg guy]

Originally posted by htg guy
These controls can wear out or fail and need to be replaced with the same style, and with the same length insertion tube.

For your safety; instead of just replacing the fan/limit, I would have a heating contractor take a look at the entire furnace to ensure that it did simply fail, and that its failure was'nt due to some other problem.

I can't find a comment from anybody telling you that these controls "stop working completely" but "not wear out slowly".

You have a problem that needs to be addressed. Its not normal for fan/limit controls to wear out every four years. Call someone and have them check over the furnace.

[zzzzzzz]

"casturbo" and "htg guy" ...

Thank you both for the advice which I will follow.