Trane XE80 furnace, no clicking, no heat, urgent

[dragondad]

I have a Trane XE80, it started to have a loud noisy sound and bad smell since about two weeks ago, then I found it was from the blower (didn't run when it has only cold air), and realize that the belt may need to be replaced, but the blower was working when heat air was push through.
Then I read the four flash lights, it indicated that the high limit switch was bad, it will stop the heat before it reach the set temporeture. And I ordered a new high limit switch, but this time, it get even worse, the call for heat didn't work, no clicking, first I think it may be the thermostat problem, but I jump between the R and W connect on control board, it still didn't start, should this mean a clean sign for bad control board, or it may be as simple as one of the switch was set to idle or turned off.
One hint, I did try to clean up the blower without unload it from track, could it touch certain switch, and force the whole system shutdown. Any idea, thanks.

[nchvac]

You probably took the transformer out by shorting out the control wires. Your blower motor or capacitor is bad. The High Limit was doing it's job. The blower wasn't moving enough air to take heat off of the heat exchanger and it was triping out the high limit, as it should.

You need to do yourself a favor and let someone who knows what they are doing fix this unit before you fry the circuit board or burn your house down. Gas furnaces are nothing to be playing with. Shame on someone for selling you the parts.

[pecmsg]

Before you do any more damage please read the site rules:

http://hvac-talk.com/vbb/showthread.php?t=186644

[keeplearnin]

Yea ditto all of the above. A sure bad sign is the bad smell coming from the blower motor. I'm also willing to bet there isn't a belt on your blower at all.

[nchvac]

how long has it been since Trane used a belt on a Residential unit?

[keeplearnin]

probably a long time

[ScorchedAir]

When the tech gets it goin, keep your filter clean. Dirty filter= no airflow= high limit doing its job