Conrol board bad or blower motor bad. Time to call a serivce company.

typhoon55 said:

carrier unit 58SX keeps shutting down after call for heat. burners fire up ok but seems blower does not kick in. one relay on main printed circuit board sparks then unit shuts down

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not an option ... this unit is in a remote area - no service avail. Did get some feedback from distributer who thinks it might be the lp fuel sensing circuit either defective or dirty contacts

I would also check the vent outlet and the drain outlet and make sure they are clear and free from debris. We have found numurous SX(C) and SX(A) furnaces that the secondary heat exchanger was coming apart and the first sign was the coating on the inside of the secondary coming off and ending up in the drain lines and vent outlets. Just a thought.

I have seen where if you blow into the vent tube it breaks a air lock which causes the shutdown. Anyway, can the vent cause an intermittent operation?

HVAC DOC,
I think your suggestion is correct. The condensate pump and tube are bone dry. This obviously should not be during heating mode.
i will check out

A good place to look is to remove the blower assembly and look up into the bottom of the heat exchanger. If it has started leaking or coming apart, it will be pretty obvious. Many times it will give a pressure switch failure code as well. Don't have the codes here with me at home but should be on the inside of the blower panel the number of flashes. If the exchanger is bad, at that point, you would need to stop and find a dealer to take care of that unit for you. Or, start looking at a new furnace.

this unit was made in 1988 pre - any lighted code panels.

I wondered if you had one of the early ones after I typed that last night. If I would of paid closer attention, I would of realized it since you weren't asking about how to decipher trouble codes. My old age is catching up with me!!

typhoon55 said:

this unit was made in 1988 pre - any lighted code panels.

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