Nate Nagel wrote:
Hi all,

still over at my friend's house... cut on heat last night for the first
time this year. He turned the heat on and went to bed; I realized after
a while that the inducer blower was running but the air handler was not.
Investigated; found that the flame was not lit, inducer was sitting
there grinding away. Popped cover, found a cracked hose between the
inducer fan housing and a pressure transducer. Cut it shorter,
reconnected, OK furnace works. But I did notice that it seems to only
run for about 5 minutes at a time, then will kill the flame, AH fan will
run for a while then shut down. Almost immediately the inducer fan will
start again, flame will relight, lather rinse repeat. My immediate
thought was that it was restricted airflow due to a gunked up A-coil for
the AC.

This evening I got over there and ripped it apart, sure enough the
A-coil looks gunky, however I could not clean it properly because I am
still fighting one rusted screw for access to it. The access panel to
the underside of the A-coil is in two parts; I removed one and replaced
the access panel on the evaporator so that some air could bypass it if
that were the problem. Unfortunately, it seems to be exhibiting the same
behavior. I didn't time how long it took it to cycle last night
(actually, early this AM - I got the thing working in the first place
about 1 AM) so I can't say if the time between cycles is longer now with
better airflow.

Now here's the weird thing. There is absolutely no nameplate, data
plate, whatever with any kind of part number that I can find on this
furnace to give me any sort of clue as to where to find a manual online
for it so I can delve deeper. Can anyone give me any hints as to where
to look?

So, I guess the question is, without knowing exactly what model furnace
this is, can anyone tell me if this is this normal behavior for this
type furnace, e.g. am I worried over nothing? I just don't want him to
have to pop for a new heat exchanger due to constant overheating.

I sadly do not have an IR thermometer - I own one, but I'll be damned if
I can tell you where it is right now.

Finally, do any of those A-coil cleaner sprays actually work well? The
A-coil is quite filthy, probably due to some ductwork pulling loose and
allowing air to bypass the filter. I'm a little concerned as this A-coil
is well past its "best before" date and when looking on the Big Box's
web site to see if my local store carried anything for this purpose, the
reviews seemed to indicate that a few people had problems with their
fins disintegrating after application of said cleaning spray. Is this a
real concern? (when I said it was past its "best before" date, I meant it.)

thanks much,

nate

Hi,
No trouble code?