philo wrote:
On 01/21/2015 09:09 PM, Terry Coombs wrote:
philo wrote:
I've got a Trane XV-80 furnace that just tonight quit.

When starting the ignitor /sometimes/ glows but most of the time does
not...and either way the furnace does not light.

I can light it manually with a match and it will run normally.

The ignigtor appears to be OK...no breaks and the resistance is 130
ohms
What voltage do they operate at and is it AC or DC?



Looks like it must be the controller itself and I know that is going
to be expensive.

Check that control board for dust/dirt , at the low voltage signal
levels
they work at it's possible there's a short circuit - especially if
there's
any condensaton/moisture present . Also possible if they used no-lead
solder
that there are tin whiskers shorting something out . Also pull and
replace
any signal-level control wiring plugs , sometimes a layer of oxidation
can
kill the signal . Had exactly that scenario happen several years ago
with a
car .




I PM my furnace every year and the control board is clean and dry.


The leads are pushed properly but I will double check,

The controller is sealed and solid state so it does not look like there
is a relay that I could replace myself.


The controller is a CNT1523 and I see them on-line for $500
Hi,
If you suspect relay, there is one for HSI It is very small. I replaced
a relay once on my old furnace with one for laser printer fuser control
circuit. Small molded piece with 4 pins sticking out, rated at
like 3 Amp./120V AC rated contacts.