Got a frantic call from the wife stating the furnace will not turn on. After having her go downstairs into the basement to monitor the events here is what she saw.

House is currently showing on the thermostat at 50 degrees, she sets it to 68 and the air immediately turns on. After 5 minutes the air turns back off and with no heat.

Following the same steps she goes down stairs, turns on and off the power to the furnace, and the air starts up again. She noticed that the rod in front of the gas blowers glows red, and stops then glows again. After 5 minutes the air stops and nothing happens.

She replaced the filter as the old one was a bit dirty, but still has the same issues. We had replaced the High limit almost a year ago.

Let me know where to start and ill get cracking. I want to exhaust all options prior to calling for service.

There should be an LED on the main control board that will blink an error code. This would certainly help narrow down the problem.

However, in lieu of that info, it sounds like the gas never begins to flow. Make sure the gas valve is open. Another possibility is that the flame sensor has gone bad. Check out this video (http://https://www.youtube.com/watch?v=iDnkdKsZhc0) for some good info (while it is on a Bryant unit, this is pretty similar to the Carrier)

The other possibilities are expensive--the gas valve itself or the main control board. Save these for last!

Good luck,
WallyH