electric furnace(moble home)
 

This furnace will not shut off in auto,it has to shut off manually..any ideas to what's causing this..

With a voltmeter and the color codes
http://wiki.xtronics.com/index.php/Thermostat_signals_and_wiring
you can isolate the problem to the 'stat or the furnace, with one reading.

If the problem turns out to be in the furnace, post the schematic, wiring and/or ladder diagram.

I've changed everything but the t-stat,fan still wont shut off..

Evidently the problem lies elsewhere or there is more than one problem.

A temporary fix for this involves the mixing together of 1 part rum and 3 parts Coca Cola. :D


The root problem may not be in the furnace after all, it could be a power quality problem causing a failure in the furnace.

In a properly designed and built unit all parts are equally likely to fail. If not, there may be a factory-published Technical Service Bulletin detailing the design defect and the recommended fix.

Strategies:
-Educated guess (you might get lucky) or
-Uneducated guess (may be costly and it still isn't fixed) or
-you take a reading, decide what it means on the spot and proceed from there (reduces uncertainty in deciding what the problem is), or
-other?