Question about Heating & Cooling
Furnace comes on and blows but no heat. Doesn't ignite. Crawled into the attic... checked the two sensors by the burner.... good continuity through the swithc. Furnace is ounted on it's side so left LED = bottom LED on the control board (slow blink) and the right LED is the top LED (always on). After checking the control board fuse (OK) and looking for burn marks ... put everything back together and it workd for a day and then quit again. Suggestions?
The ignitor can crack and cause this, also check and clean the flame sensor.
Posted on Nov 25, 2013
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Posted on Jan 02, 2017
Ok, you either have a inducer fan issue or a pressure switch issue or a plugged vent pipe. The inducer turns on to establish a draft for the exhaust. If it is not working you will get this error code. If the pressure switch does not sense pressure caused by the inducer, it will give this code. If either the intake pipe or exhaust pipe is blocked (even y just a little) it will give you the same error code. If the condensate hose or receptical is plugged, again it will give you this error code. Good Luck!
Posted on Oct 21, 2008
sounds like the circuit running to your condenser powers your furnace. when u disconnect power to the furnace it will reset and run the blower on startup. check the tube connecting the vacuum switch to the induced draft motor. maybe a leak. good luck
Posted on Nov 24, 2009
Maybe, look for bad wiring connections and retighten the ground wires from circuit board to cabinet. Take a can of air and clean the burner tubes being careful not to blow on the igniter. Are ther any error codes blinking when it does not light? Read on for some more tips.
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).
Posted on Dec 29, 2009
if you have replaced the flame sensor and it will not stay lit, the draft safety switch may be opening. It works on positive and negative pressure created by the inducer fan motor.You may have a restriction in your heat exchanger or if is a high efficiency furnace, it may not have the drain tube installed properly with a trap. The trap works just like the trap under your sink and if water isnt in the trap, the pressures can be effected enough to open the draft switch(some call it an air pressure switch)
Posted on Jan 07, 2010
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