Trane XE90 Furnace
 

I have a XE90 trane furnace that stopped working. If you raise the thermostat to start the heat it clicks on but the intake doesn't pull air in. We aren't sure if it is the thermostat or a transformer. There is no reset switch that I can see. I don't have any info on this Trane. We only bought the house 2 years ago. The unit was purchased 7 yrs ago, by the previous owner. Can anyone help?

Sounds like the 'former works, the 'stat is asking for heat and a relay is pulling in.
If you can the find the relay that is clicking measure the voltage across the closed relay contacts.
Less than 30 millivolts is good and more than 100 mVac is bad.
This is a $10 part depending on where you buy it.

Post whatever numbers and letters are on the relay case.
http://www.r1200gs.info/howto/images/relay-1.jpg