I have a problem with my gas furnace that's been going on about a week. When the thermostat is pushed up, the fan comes on. Sometimes the gas will go ahead and fire up and sometimes it won't. Sometimes when the gas fires up, the blower comes on. Other times the blower doesn't come on and the whole thing shuts down. Then you can't get it to do anything for several hours, in which case it will come back on normally again. It will work a few hours and do the whole thing over again.
The furnace is a Rheem criterion II. We've owned the house for one year, and the home inspector estimated the age of the furnace to be 7 years old at the time of purchase.
We've check to make sure the filter is clear. My husband also installed a new thermostat, but the problem is just the same.
Any ideas??? Could this be something serious? I really can't afford a new furnace right now!