I have a Carrier 58mxa 080-16 gas furnace. Installed 1/30/04. When heat is called for the hear goes on and the blower motor starts with 60 sec delay. The blower motor goes off after @ 10 min even though it has not reached desired temp. Immediately after it shuts off the heater starts up again but blower motor does not come on. After @ 5min the heater shuts off. If I turn off the electric and turn back on the heater will start again and blower motor comes on at 60 sec and then repeats above. I changed filter 2 weeks ago and it was long overdue. I changed filter again yesterday since new filter was somewhat dirty. Looking back, I think the blower motor has not been coming on consistently the past few weeks, but yesterday is when the house could not get above 66 and I started tracking on/off timing. Blower motor will go on manually. Above is when bm is on auto from thermostat. I suspect some cut off safety part is intermitently going bad. I have just taken off covers and dusted

Optional Information:
Make : Carrier WeatherMaker 9200
Model : 58mxa 080-16

Already Tried:
replaced filter for intake on side. Also removed both covers and vacuumed and dusted all I could get to.