I need a manual for coleman dgat070bdf furnace

check to see if gas valve has a pilot position if yes then have to lite it if no then has ignitor

That’s a model number for a mobile home furnace. The flame sensor is inside the burner chamber. You have to turn the gas off, remove the screws that hold the two plates around the gas valve, and pull the whole burner assembly out. Be careful of the igniter, and don’t use sand paper on the flame sensor ??

Is it natural gas or propane? If propane, make sure you are not out of gas. Does it have electronic ignition or a manual pilot? if pilot, make sure the pilot flame is still lit and the control knob is turned to the "On" position. If it has electronic ignition, shut off the power to the furnace and then turn it back on and see if resets and lights.

There is really not enough information here to go on. If this furnace has a thermocoupling, the pilot will need to be lit manually. Follow the manufacturers lighting instructions carefully. If it still will not light you may have a dirty pilot assembly or a defective gas valve. Modern furnaces do not use a thermocoupling. There is no standing pilot light. Each time the furnace needs to be lit it will be done electronically. Many reasons why it wont light in this case. Safety control could be preventing it from lighting for safety reasons. A bad ignitor, ignition module, circuit board, gas valve, pressure switch, gas supply, induced draft motor, blocked or restricted flue pipe, cracked heat exchanger, dirty flame sensor, ect. ect. ect.

For sensor if you mean thermocouple that sits in the pilot light I say this is usually the problem. The thermocouple needs to heat up to a preset temp before it will allow the gas to remain on. Does the pilot light stay on? If so make sure you turn the gas knob to on from pilot/light

Heat exchanger could well be split causing it to blow out pilot

Hi check the flame sensor is clean also check out the pressure switch , and check air filter is clean

Go to www.grainger.com and look for a "power pile generator" this is a millivolt thermocouple that may be just what you need to make your heater work again

Have the thermocouple replaced, ensure the pilot flame is blue - not yellow, yellow indicates blockage in pilot

There is a thermocouple "wire" that is supposed to be touching the pilot flame.
The thermocouple senses a flame (hot) and allows the heater to operate. If the thermocouple does not sense that the pilot is on, then it will not allow the furnace to operate.
Bend the thermocouple wire (or the pilot tube) so that the pilot flame is touchingg the thermocouple.

That shouls work now.

The air from the fan should not be blowing through the same cxavity that the pilot is in.
If it is, then you may have a leaking furnace whereby carbon monoxide may be seeping into your living quarters.
If the fix above works and the pilot stays on after the heater starts, then there is probably no leak.

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