 
 
				Responded to no heat complaint on 5-year-old furnace that was shutting down after 15-20 seconds of operation. Diagnosed pressure switch issue with fault code indicating "pressure switch stuck." Upon testing, identified one of the dual pressure switches exhibiting slow response and dull sound when manually actuated. Replaced faulty dual pressure switches, restoring normal system operation. Unit should still be under parts warranty.
 
                                