Intertherm E2EB-017HB

I woke up to a hazy smoke filling my house one night, when i walked up to the Cabinet for this thing, I could feel the intense heat coming off of it. while fooling around with this thing I discovered that when the thermostat was switched to A/C and running everything seemed fine. as soon as the house hit the temperature the A/C would cut off and the blower would stop spinning, but the Heat Strips would immediately come on and get very hot, very fast. I switched off Circuit B and left Circuit A on (2 60 amp breakers on the unit), the Air Conditioning runs fine, and the Heat strips don't come on. Is this more likely to be a bad sequencer, Limit Switch, or the actual Element going out. I haven't yet taken anything apart to look, but i was hoping someone had an idea on this so I have a general idea of what I'm up against.