Our furnace began to shut down after running in Heat for few minutes and I have to turn the termostat off for few minutes before restarting it. After several cycles the furnace stays on until reaching 70 degrees from the 58 that usually maintains if I do not play with the termostat. We insert new batteries but this did not work. do you think is the termostat or is a problem with the furnace. Best Regards The termostat is the model 1F86-444. Thanks. carrilac2@hotmail.com