Check the date on the OP. It’s been well over a year. Hopefully her problem has been fixed by now.
All of the above is true, but I’ve also had gas furnaces do this short-cycle thing when the thermostat did not have an adequate temperature hysteresis - there should be a degree or more between the temp it turns on and the temp it turns off. If the band is too narrow, it will jitter between on and off until the house temp drops another degree or so. The test is to force the furnace on by turning the thermostat up several degrees - if the furnace kicks on and runs fine, replace the thermostat.
I thought I’d piggyback on this old thread with a similar problem. I have a cheap Goodman furnace in a rental house that just had an ignitor fail. I replaced the ignitor and now I notice it takes two cycles to fire. The new ignitor glows just fine, but only for a second or two before the gas valve opens. The first time it doesn’t light and shuts down. The second cycle, the same thing happens but the burners ignite. I thought the ignitor was supposed to glow for much longer before the gas valve turns on.
I don’t know if this was happening before the ignitor replacement. Could it have anything to do with that? Is there an adjustment for this, should I get a new control board, or any other ideas?
Thank you. This is my first post here and I’m impressed with the replies above.
Hi All,
I am having almost the same problem:
when the heater starts, I can see the gas blower starts, then the gas starts burning - the burners roaring away for about 30 second or a minutes then the burner stops before the main house blower starts. So when the main blower run, it just blow the cold air (without heat) so the processes keep doing over and over. If I turn off the heater from thermostat and turn off the main furnace power completely then turn the eater back on again then the heater will run as normal for several cycle then repeat the same problem. I would like to replace the board controller but just want to make sure if it is the right thing to do. Any help would appreciated.
Thank you-
Get the make and model number of the board and do an internet search and see if you can find a sequence of operation for the board. A sequence of operation will give the timings of the various components as they start and run.
In other words, first the thermostat calls for heat. The induction blower and the igniter are energized. X number of seconds later, (usually 15-30), the main valve is opened and the burners ignite. X number of seconds after that, perhaps 30-60, the blower will start. See if your furnace is operating as it should.
I’m wondering if the high limit is opening and shutting down the burners. Either because it’s defective or because the board itself may not be starting the blower in time. Or possibly my experience below.
My furnace, a couple of winters ago, was doing something similar to what you describe. In my case, the capacitor was bad on the blower motor and the fan didn’t start when it should have. High limit shut off the gas and the unit would attempt a restart. It would apparently work some of the time or at least the second time because the house never got cold and it ran half the winter before I discovered there was even a problem. (I happened to be in the basement one evening when it shut down and then ran properly the second time.)
I’m a retired HVAC tech and I thought it was the board gone bad. I put in a spare I had but that didn’t help. Eventually I put a meter on the capacitor and found the problem.
It’s not likely that’s whats wrong with yours, but it’s something to consider.
Thank you Dunno ! I tried to reset the power again last night but it did not work like it used to be - I meant for the last couple months, everytime I reset the power, the heater will run as it suppose to for several cycles but now, the burner stopped before the main blower start - it seems like the blower working fine - the only thing is I don’t know if the flame sensor bad or the whole board but I think this is a good time to replace the board control - unless there is a better way to troubleshoot to isolate the problems.
Thank you-
It’s hard for me to troubleshoot from this distance, but it may very well be the board. Also could be the flame sensor. Have you tried cleaning it? Sometimes helps.
And like I said above, it COULD be that the blower is coming on too late, causing the burner to go out on the high limit. How long does the burner stay lit?
Does the unit have self-diagnosis?
Is it flashing a code?
Can you switch the fan to “on” (instead of “auto”) - does the blower (air mover) come on and stay on?
My furnace just experienced a flame sensor problem plus another problem.
It was kicking on then off after a few seconds, so I cleaned the flame sensor, it would run for a little longer then turn off. So I ordered a new flame sensor. Put it in, same thing, on for about 30 seconds then off.
I did some head scratching and eventually decided to pull off the hose from the pressure switch after it kicked off. The end of the hose was loose and also warm.
So I pressed it on tighter, problem solved.
Since this was originally posted in 2012, I expect it is fixed by now.
We are trying to help caoboys who posted in this thread with a furnace problem this week. I’m aware it’s a zombie but evidently you didn’t read through the whole thing.