Help with lennox furnace will not stay on.

slowhand · 12-06-2009, 10:18 AM

I have a Lennox G24M2-60A-10 and it will not stay on. It comes on for a few minutes then shuts off. The blinking light code suggests "prim. limit open" which from reading forums could be a dirty filter. So I replaced the filter with a new one and same problem. But I ran the furnace without the filter just to see what would happen and it ran fine. I know running it without a filter is bad so how do I fix the problem? Any thoughts and advice would be greatly appreciated. Thanks slowhand

yuri · 12-06-2009, 10:53 AM

Make sure all your vents/registers/dampers are open. Check the underside of the A/C coil for dirt buildup if you have one.

slowhand · 12-06-2009, 10:59 AM

Hey thanks for responding Yuri. I checked the air vents and there open but not sure what or where the A/C coil is.

Houston204 · 12-06-2009, 08:40 PM

The evaporator coil is usually above the furnace in a vertical application,
It is much easier to access and clean in a horizontal application.

marchvac · 12-06-2009, 09:10 PM

Have you ever left the filer out of the furnace for a period of time during the heating or cooling season. What brand of filter did you install.