I have a Carrier crawlspace gas furnace. For some reason the tube connecting the draft blower to the vacuum sensor is heating up - it loses seal on the blower and the vacuum leak prevents the rest of the heat cycle. If I cut 1/2" off, the furnace works fine and will continue to as long as there are regular cycles. If there is a warm day, the tube fails again and must be cut.
The tube was replace about a year ago as the original was rotten. The replacement tube is for these vents. The tube is black, but changes color at the fitting on the blower and periodically on the vacuum sensor.
Any suggestions as to a cause?