Trane XE 90 not giving heat

[winner155]

I was traveling and my wife told me we lost heat. Assumed we ran out of gas. Had gas delivered today but when I got home this afternoon, one furnace for the apartment we have was running fine and the one for our house was only blowing cold air. The fan works, the thermostats seem to work fine but when I look at the furnace through the vents, the flames from the gas are not there and no heat is coming out of the registers. What i thought was the problem is clearly not right as the one furnace is working fine. Can anyone guide me on how to troubleshoot and fix this problem? I really do not want to call a repair guy on the weekend if I can help it. that would cost a minimum of $300 where I live. Thanks

 

[paul52446m]

when you turn stat down for 5 min. stand in front of the furnace, turn up heat and what happens.?
Is this a newer furnace or a old one?
It a 80% or 90% ?
This is LP gas ?
Is it spark or glow bar to lite burner?
What brand is it? Did you run out of gas?
Is it a up flow or down flow ? Paul

 

[hvactechfw]

check for a diagnostic trouble code viewable through the blower door window.