Lennox Pulse Inducer/ Purge blower runs continuously

shooter88

Hello- I have a late 80's G14 Lennox pulse that continues to run like a charm... except for the inducer blower(also heard it called a purge blower) running most of the time. Symptoms as follows; purge, ignition, burn, and cycle off are functioning as normal. When the furnace is not performing any of the above, the inducer will run for 30 or so seconds (as if preparing to burn), then will cycle off and in one or two seconds cycle on again... effectively running continuously between when the furnace actually burns. Occasionally the inducer blower will be off as expected when the furnace is not preparing for ignition, but I havnt found a pattern to when this happens.

I have tested some things suggested on grayfurnaceman.com but havnt found anything conclusive. Has anyone experienced this symptom/know the cause? Any suggestions on what to check would be appreciated.

EBEBRATT-Ed

Sounds like a control board issue.

Your probably way over the limit of the life expectancy of that furnace

shooter88

Thanks Ed- I was wondering if that could be the issue based on something I read elsewhere, and the fact that I can tap on the control board and occasionally that will shut the purge fan off.

I am pretty tickled to have gotten this long out of it, but financially am trying to make it work 'one more year'. I may just not be able to nurse it along like that this time.

mattmia2

Does it still do it if you disconnect w from the control board or t-stat?

SuperTech

I'd make sure to have that Pulse pressure tested if you are planning on trying to keep using it.  The G14s are notorious for heat exchanger failures. I wouldn't attempt to repair anything until unless you know that it is safe to operate.  

You have definitely got your money's worth out of it. That furnace is well past its expected lifespan.