I was hoping to get a little help from the masters of HVAC. I'm having trouble diagnosing a tempstar furnace. The blower runs all the time. Even without the t-stat being wired to it. It has intermittent spark ignition. I changed the board, but that didnt do anything. Would it be the limit switch? and if so can I jump it, to see if that is the problem. The wiring diagram shows a normally closed limit switch. Any help would be awesome.
ICP and Carrier will run the fan continuously if the limit is open (to cool off the hot heat exchanger is the rational). You can test it with an ohmeter. I will never recommend jumping them as some fool may leave a jumper on for "temporary" heat and kill someone.