These days new high-efficiency furnaces do not put out hot blasting air, it's rather lukewarm. Is there a possibility your heating ducts are fed through a uninsulated space? Your first and best step would be to contact a dealer that installs and services York.
Once upon a time,in America, everyone had big old furnaces with big heat exchangers. The homeowner would set the thermostat and the burners would light in the big old furnace. The temperature would begin to climb inside the old furnace: 100, 110 degrees and the furnace would growl "Give me more heat". 120, 130 degrees "More heat" growled the furnace. To not make the homeowner ill, the furnace would allow the bad gases, and 1/2 the heat to go up the chimney. Finally, somewhere between 140 and 160 degrees, the furnace would roar and say "I am hot enough, I will now heat your house". When the fuel bill came the furnace was happy, the fuel company was happy, but the homeowner was very sad.
One day the village furnacemaker wondered if he could make a better furnace. He designed a smaller furnace with a smaller heat exchanger and a very high speed fan. He removed the old furnace (no small struggle that was) and installed the new furnace. He turned the furnace on and began to watch the heat rise.
Lo and behold a miracle occured. Somewhere between 80 and 100 degrees the furnace called out "I am hot enough, let me heat your house". After he received the fuel bill, the homeowner became happy, the furnace was happy but the fuel company was very sad. Of course he then raised his rates to make himself feel better.
The moral of the story is that your furnace is probably working normally, but, to satisfy yourself take Mike's advice and call in a York serviceman. He will probably charge you around $80+ for the service call. If you insulate your home it will remain much warmer and save you the money for the insulation in about two years. Hope this helps...