Joseph wrote:
"Bill" wrote in message
ups.com...
I have a furnace

Model# Serial# may be of help.

Joseph, thanks for your input on this. The furnace is a Trane XV80,
TUD100R9U5K; Z291YLRIG



The flame sensor does exactly what you would think it does. It
senses
current rectification through the flame to ground. The control
module looks
for that current after it opens the main valve. If it is not there
then the
system goes into lock out. Each unit is a little different but the
basics
are the same for all.

Is the current in the sensor all of the time, or only after the valve
opens?


Is the guy working on it the one that installed it? You might
want to
call the Mfg and explain the situation to them and see if they can
remedy
the problem. It's hard to tell what other possible solutions there
may be
w/o being able to put my hands on it, I can only make a WAG. This
may be a
bad Molex plug, wire connector slowly deteriorating, piece of debris
in gas
line... etc...

Yes, the same folks that installed it are the ones trying to repair it.
What is a Molex plug?

Thanks.

Bill