I have a 19 year old York Stellar furnace. Model P1UCD12N04601B 57,000 btu's. This unit was salvaged from a military housing complex that closed in 1990. The unit shows very little wear. All the parts look new. The unit sat no operational for nearly 16 years. I removed the unit from the house myself.
When the unit starts up the exhaust blower is the first to go on. This activates the ignitor via a vacume switch, ignitor reaches temp and gas kicks on. The unit heats up then the updraft blower starts. This is all normal operation to this point.
After about 1 to 2 minutes of the blower starting the blower kicks off and continues this 1 to 2 minute cycle until the thermostat reaches temp. AM startup of the heater usually runs about 1/2 hour. After the burners go off the fan continues the off and on cycle until the unit cools down. Is this a relay problem in the control panel at the blower compartment or something else? I really need some advice before my blower burns out from all the starting and stopping.

Thank You
overland48

If you leave the temp setting down low at night then the cool air in the house will cool the fan switch very fast in the mornings. There will be some heat left in the furnace box that may be heating the fan switch back to the on position. If this is the case it may be that the differential on the fan and limit switch is too close or maybe the switch is bad. If you can adjust the switch the setting should be on around 130 to 150 F and the fan off temp should be 95 F. If this does not work give us more info of just how it is acting in the mornings. I don't think you aare going to hurt your motor unless this starting and stopping is going on for an hour or so.