I have a Nordyne KG7SA, about 2009 vintage, which has begun acting strangely. We started noticing that the thermostat would drop several degrees below the set temperature before engaging. More recently I started noticing it seemed to cycle very quickly several times in a row, then just quit. Then on Christmas Eve it stopped working altogether.
I was able to get it working again by turning it off and back on again, but it would only run for ten minutes or so before starting the short-cycle routing again, and shutting down.
After doing some Googling I came opon the thought that the filter might be too dense (it was one of those 3M "allergenic" filters). So I removed it and the furnace began working normally again.
Today (12/26) I picked up a new, lighter filter and the quick recycling started happening again after a few rounds of heating. I had the presense this time to observe the status code - alternating blinking red and green - which I'm led to believe indicate a one-hour lockout mode. This seems to be consistent with the delayed cycling we'd observed in the past. (Side note - why are these status code legends so hard to find online?) When the filter is off and the unit is operating normally the status lights are solid red and green.
So in my most uneducated estimation it seems my furnace is having some sort of air flow issue.
One other point I should add - my dehumidifier filter is in dire need of replacement. It's a GeneralAir 1099LHS and I'm having a hard time finding new filters for it. Could this be contributing to the air flow issue I'm experiencing? If I set it to summer mode and bypass it (in the short term, anyway) might this alleviate the issue until I can find a replacement?
My main questions are, do I seem to be on the right track in my diagnosis? What would be some logical next steps to troubleshoot and isolate the issue? What might be some low-cost things to try in an attempt to solve the problem?