On 11/4/19 1:48 PM, trader_4 wrote:
On Monday, November 4, 2019 at 8:22:50 AM UTC-5, Dean Hoffman wrote:
On 11/3/19 8:44 PM, Chris wrote:
I have an older Trane XL1200 gas pack furnace/AC. I just tried to turn
on the
furnace and nothing happened. Looking at the control board the led code
told
me it was a pressure switch problem. The inducer fan was not turning
(rusted
stuck). I replaced the inducer fan and now the furnace will go through the
start-up sequence (checkÂ* high limit switch, check flame rollout switch,
turn
on inducer fan, check pressure switch, turn on spark igniter, send
voltage to
gas valve) but it fails to light and goes into system lockout (no flame). I
checked the voltage to the gas valve and it was 60V AC while the igniter
was
firing! The gas valve would click but the furnace would not fire. It
should be
24V AC. To check the gas valve I disconnected the wiring from the valve
and I
connected 24V AC to it and it would click but I could not hear gas
flowing or
smell any gas. Do you think the gas valve is bad or the control board
since it
is supplying 60V AC to the valve?

I'm a bit surprised that 60 volts didn't fry the gas valve. That's
about 2.5 times
what it's supposed to get.

24v he said. I wonder if this is a measuring problem, operator error?
What happens if you have the meter set for DC instead of AC? I've done
that, but don't remember the results. Hard to imagine there is 60V
there, as the control board would just have a relay that it closes to
apply 24V from the transformer to the valve. I suppose the transformer
could have a short, be bad, but seems that should have cooked the board,
blown a fuse, etc.

But he said he applied 24V to the valve, it clicked, no gas. That would
seem to indicate a problem with gas supply, debris in the valve, etc.
I've seen furnaces have no gas due to the pipes corroding underground
and filling with water. I'd work on checking for gas, then unhooking
the gas pipe, energizing the valve and try blowing in the pipe to the
valve and see if it passes air.

Other funny thing here is he said it started with the inducer motor being
rusted and bad. Usually you only have one problem. Wonder how long this
thing has been sitting unused?

Maybe it's one of those really silly things one assumes is right.
Is the gas on at
the meter type of problems. I wonder if he has other gas appliances in
the house to
use for reference.