Question about Coleman Heating & Cooling
Trying to restart a Coleman Oil Furnace Model 8870A. It appears I am getting good ignition but the main burner just will not light. Already tried cleaning the ignitor leads and have been experimenting with the adjustment for air... Any ideas?
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Posted on Jan 02, 2017
If you haven't already tried Coleman customer support, try Google. You can find owner's manuals for all kinds of things. good luck, John
Posted on Nov 07, 2008
If you have a volt ohm meter take the two leads off the gas valve and ohm out the connection should have resistance for the coil. You said you have 12 volts from the thermostat white and red in the heating mode you should have minimum 26 volts. If you want to check the transformer should have 28 volts. Almost sounding like the transformer is getting weak. You can get parts for a 20 year old unit at any HVAC parts house. Try Washer Specialties here in Wichita Kansas they are on the web. Lowes even carries Transformers. Has to be rated 120 volt primary side secondary side 24 volts and 40 VAC.
Posted on Nov 24, 2008
On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the igniter. The igniter will glow and you will be able to see it if viewed thru the small inspection port. Once the igniter gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.
What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the igniter does not energize (bad control, bad igniter), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not light (dirty pilot), the burner does not light (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).
Your furnace has a diagnostic chart on the reverse of the lower panel incorporated in the wiring diagram. One blink tells you that it is a failure but wont tell you where to start looking.
Posted on Nov 28, 2009
if the reset is a square button see if this will work. hold the button in, the green light will go out, count to 30 by 1000s, (1001-1002-1003 etc.) at around 1030 the green light should flash once. when it does release the reset and wait about 10 sec. the pump should start. if it runs for about 15 sec. and shuts off the pump needs to be bled. good luck, hope this helps.
Posted on Jan 22, 2010
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