My Mother-in-law has a Trane XE60 furnace & the pilot light is blue but only blows cold air when the thermistat is at the on position. When the thermistat is set to auto at 80 degrees nothing happens. She thinks the pilot light might be a bit weak. I've seen in some of my research that there is an adjusting screw somewhere & can be found in the owners manual but we don't have one. Tried downloding & they wanted to charge me. Any advice? Rob

If the piolit light is week, odds are it will not stay lite. Did this just start happing or is this the first time she has tried to use the furnace this yr?

Is the gas valve on on position,

My heater is having the same symptoms and yes the gas valve is in the on position. So the fan comes on, but only blows cold air, and in auto it does nothing. It did this two days ago and with some banging, opening up the unit and putting it back together again it worked but now it is doing the same thing.

I have this model and have had the same problem, even had a technician come out to tell me it was the thermocouple that was bad, replaced it myself and relit the pilot light and everything was great, I was able to get the thermocouple at my local Orange home improvement store