Looking for some help with an on-again, off-again issue dating back to October. Thermostat calls for heat, but inducer doesn't come on but once in every great while (24-48 hours) when I power-cycle the unit, and when it does only for one cycle (heat works fine for 15-30 minutes). From October to now, the system worked in fits -- fine for 3-4 weeks then out for 3-5 days, always going out the night of a sharp temp drop and coming back unexpectedly.
Anyway, it's been out a week solid now (save the stray cycle every 2-3 days). We've tested the roll out and limiter, changed out the pressure switch (and checked the tubing & condenser box). We've also changed out the thermostat and checked the flue. The issue is somewhere else between the thermostat and inducer. On an outside recommendation based on a similar problem and having checked everything else, we're down to the board, which is, of course, the most expensive link in the chain by far. I don't mind the cost to be rid of the problem, but considering there's no return on this (or pretty much any) part, I'd like to have some sort of indication that this is the likely culprit.
There is no burning on any connections on the back of the board, or even any "haloing" of the solder joints. When it's powered, there's a little white ceramic block at R10 that gets pretty warm and a ceramic cylinder at R20 that does too -- this one shows some very slight yellow on the board around it. The board is working well enough to call for the A/C unit and even the blower, just not the heat (inducer). It's an Aire-Flo furnace, Honeywell ST9160B1076 board. Any advice on this would be greatly appreciated...
Anyway, it's been out a week solid now (save the stray cycle every 2-3 days). We've tested the roll out and limiter, changed out the pressure switch (and checked the tubing & condenser box). We've also changed out the thermostat and checked the flue. The issue is somewhere else between the thermostat and inducer. On an outside recommendation based on a similar problem and having checked everything else, we're down to the board, which is, of course, the most expensive link in the chain by far. I don't mind the cost to be rid of the problem, but considering there's no return on this (or pretty much any) part, I'd like to have some sort of indication that this is the likely culprit.
There is no burning on any connections on the back of the board, or even any "haloing" of the solder joints. When it's powered, there's a little white ceramic block at R10 that gets pretty warm and a ceramic cylinder at R20 that does too -- this one shows some very slight yellow on the board around it. The board is working well enough to call for the A/C unit and even the blower, just not the heat (inducer). It's an Aire-Flo furnace, Honeywell ST9160B1076 board. Any advice on this would be greatly appreciated...
