If it is a new trane furnace with a heatpump then it most likely does not have a piolit light. Turn to emergancy heat and see if it works that way

How do I do that? We installed it in 1999. It is blowing cold air only. The only model number I see is YCC042F1M0BF. I am not sure what panel to open on the unit.

Is it a heatpump with electric furnace, or gas?

At the thermostat change it from heat to emergency heat

It is gas.

Are you sure you have a heatpump, or just a gas furnace and ac?

If you have not emergancy heat at the stat, then turn it to heat. Go to the furnace look in the at the bottom door for a flashing fault code light.

Ok, I have Trane A/C and gas heat. It maybe called a furnace. There is no emergency heat option at thermostat. Just Heat on/off, Cool on/off, or Auto.

If you have not emergancy heat at the stat, then turn it to heat. Go to the furnace look in the at the bottom door for a flashing fault code light

You can alos try turning off the main breaker to the furnace this will sometimes reset the fault, but try to look to see what it is flashing first.

I assume the bottom door is a panel on the outside unit? Then what? Is there a way the reset or go from there?

The bottom door of your inside unit

Ok, all that I have is a thermostat inside and a door to change filters inside. Everything else is outside. Gas meter is next to unit outside.

OK you have a gas/ electric package unit. Then the door you would need to take off should be where the gas goes into the unit, is the blower running now?

Yes, blower is running. When I put my hand over the exhaust it is cool air blowing out. That should be warm or hot correct? Is there a panel on the unit I should check?

Open the unit where the gas goes in. look for one of these.
Should have a red reset button in the middle.

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Only switch I see is a switch that say M1, P3 or C2 and the switch will go to an off / on position. It is currently in the "ON" position. I flipped it off and back on. The gas line looks like it goes underneath and branches to four small cone or funnel shaped arms.

Keep looking there must be a small limit switch somewhere they are the only things that keep the blower running. Usually they are hooked with red wires so if you see red wire follow them. Or you can post a pic of the inside of your unit on here

I have pictures, how do I post them?