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supply and return ducts, attic was 3/12 ducting work was done by another company and never finished the job.

Let me know what you think. Disconnect is the new 60 amp with GFI plug inside the box. Works great and looks clean.
http://img157.imageshack.us/img157/5272/678386822orig7rt.jpg...

tell me what you think
http://img492.imageshack.us/img492/6109/678377299orig8xe.jpg
http://img163.imageshack.us/img163/499/678377303orig0dk.jpg...

sounds like a low voltage short, causing internal transformer overload to open and by the time you move it to other furnace it is cooled down and works.

Is the furnca installed as horizontal left with the inducer motor at the top of furnace, whatsize btu's. If over 90,000 or horizontal left order a vent drain kit from manufacturer.
Shorten drain...

HAVE A CONTRACTOR WITH A INFARED INSPECTION CAMERA TEST THE HEAT EXCHANGER. AND CHECK STATIC PRESSURE TO DETERMINE PREMATURE FAILURE IF OVER .5 IN. W.C. HAVE DUCTING REPAIRED.

try a "fanhandler" converts almost any existing motor with a good service factor to variable drive controlled by temperature