Furnace blowing cool air

[bethadee]

I have gas heat and lately have noticed that when the furnace comes on it is initially blowing warm air, but after that it comes on and only blows cool air (thermostat set to 65, cool air feels less than that, maybe in the 50's, but certainly not as cold as the air outside in the 20's). So this doesn't seem to be an ignition problem since it is warm at first, but does anyone have any idea as to why it only blows cool air after that?

[Daltex]

Does the indoor temp drop below 65* ? If so you may have a bad gas valve or sensor or thermostat blocked flue or......- Time to call a pro. If it stays at 65* then could be a bad sensor or bad limit switch or bad stat or....- Time to call a pro

[ECIndHVAC]

I bet that if you put a thermometer in the register when the furnace is blowing "cold" air, you will find that it's actually pretty close to 65