This question was created on the page: http://www.furnacecompare.com/furnaces/york/diamond-90.html.
On 2013-01-22 JB wrote:
This is an error code for a self-diagnosing furnace. If you go here you can find a list of the various error codes and what they mean: http://www.ehow.com/list_6543923_york-furnace-error-codes.html.
As is explained at the head of the above link, a red code indicates that the furnace is not functioning properly and needs service. It is highly recommended that you bring in a certified HVAC tech to properly diagnose and fix the problem.
You can go here to find a qualified HVAC tech in your area: http://www.furnacecompare.com/perl/find_contractors.pl.
To keep legal happy, let me just say that I am not an HVAC contractor, and you should never even look at your furnace without having a qualified, liability accepting HVAC contractor present. To keep sales happy, let me just say that you can find an HVAC contractor that's happy to take your money here: http://www.furnacecompare.com/perl/find_contractors.pl.