I have a Heil outdoor Gas/AC pack model #NPGAD24D1K3 approximately 10yrs old. Unit works great as always at heating the house. The unit cycles normally; however recently I noticed that in between heating cycles the exhaust blower turns on and off repeatedly about every 10 seconds. Approximately ten seconds on, then ten seconds off. It only does this in between heating cylcles when the thermostat switch is set to heat but the thermostat is not necessarily calling for heat due to temperature in house. The exhaust blower does not do this if the unit is cycling. It comes on normally at the beginning of the cycle and runs contiuously during the cycle just like it always has, and then stays on about 20 to 30 seconds after burner cuts off just like it always has. Only in between cycles does the exhaust blower act up. If the thermostat is set to off, the exhaust blower does not come on. I am comfortable switching out parts on this unit, if someone can help me with a diagnosis. Any help would be greatly appreciated.

I have a Heil outdoor Gas/AC pack model #NPGAD24D1K3 aproximately 10yrs old. Unit works great as always at heating the house. The unit cycles normally; however recently I noticed that in between heating cycles the exhaust blower turns on and off repeatedly about every 10 seconds. Approximately ten seconds on, then ten seconds off. It only does this in between heating cylcles when the thermostat switch is set to heat but the thermostat is not neccesarily calling for heat due to temperature in house. The exhaust blower does not do this if the unit is cycling. It comes on normally at the beginning of the cycle and runs contiuously during the cycle just like it always has, and then stays on about 20 to 30 seconds after burner cuts off just like it always has. Only in between cycles does the exhaust blower act up. If the thermostat is set to off, the exhaust blower does not come on. I am comfortable switching out parts on this unit, if someone can help me with a diagnosis. Any help would be greatly appreciated.
This looks like an issue I have just had. It may be that the exhaust blower (draft inducer, technically named) might be bad. One thing I would suggest you to do, is to disconnect this motor and run a couple of wires direct (make sure first that it is getting 120V when it is running before you do this test).

Once you connect it, also verify that it is the proper rotation, if not, just switch the wires.
The proper rotation is to ensure that you are simulating the normal operation. Once you get it running, stay there for at least 20 minutes... if this is the probem, it should fail within this timeframe. If after 20 minutes it kept running, do it again at least three times on 20 min intervals. When these motors start malfunctioning, they may go from longer periods working OK, then it will be minimizing more and more. If it fails... you have got the culprit.