I have a Trane XV90 MFG in 2004. I get 21 bliks of the green light and one red. I think that is OK and no error code?
The thermostat is on and no ignition sound at all? The Fan turns on when it is on ON position. I have turned off and thurned on the main switch and reset the unit but no Luck? Any suggestions? Thank you...

Turn off the power to the furnace.Try removing the thermostat from its subase and disconnect the wires at terminals "r" & "w" connect those wires together. Turn the power back on, if the furnace turns on the issue is with the thermostat. If it doesn't turn on, turn the power back off and reconnect the wires back to "r" & "w". Go to the furnace and remove the wires connected to "r" & "w" at the control board. Install a jumper wire between terminal "r" &"w". If the furnace turns on now there is a break in the wire between the furnace and the thermostat.
"r"(24v power) might be "rh"(24v power heat) at the thermostat.