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White Rodgers Gas Furnace Ignition Control Board
Electronic Ignition Gas Furnace Problems Troubleshooting - Gas furnaces are a prevalent form of heat for homes and businesses, and occasionally a gas furnace needs to be repaired because of a problem with the gas furnace.
Since there are many different types of gas furnaces, it is difficult to cover every single possible gas furnace problem that can occur with a gas furnace in one article. We are going to break this theme “gas furnace problems” down into a series of articles with the first one being gas furnace problems with electronic ignition gas furnaces.
Electronic Ignition Gas Furnace Problem Troubleshooting: Understanding Sequence of Operation
There are different levels of problems that can occur with any gas furnace. The most common failure is electronic ignition failure. That is quite common with gas furnaces. Knowing how to troubleshoot a furnace problem is key to solving the problem.
Another common fault is the failure of electrical systems on a gas furnace. Both of those failures can be the same. Consequently, that is an electronic ignition failure can be the result of an electrical fault in the system somewhere.
And when I say electrical failure with a gas furnace problem, I am speaking of controls. Or control wiring with the gas furnace. To break it all down, we begin with the sequence of operations with a gas furnace. Furthermore, this is very important to understand if we are to troubleshoot the electronic ignition gas furnace problem.
The Sequence for Most Electronic Ignition Gas Systems
Electronic Ignition Gas Furnace Problems and Troubleshooting
On most electronic ignition gas furnaces sequence of operation but not all the sequence will occur in the following manner:
The Sequence of Operation - Electronic Ignition | Electronic Ignition Gas Furnace Problems and Troubleshooting
- Call for Heat
- Control Board Initiates
- Induced Draft Motor Turns On
- Safety Circuit Check
- Ignition Process Begins
- Flame Proving
- Main Burners Fire
- Blower Control Initiates
- Thermostat Satisfies Setpoint
- Shutdown Sequence
1
Call for Heat
Call for heat at the thermostat. The house is cold, and the furnace needs to come on to heat the house. The thermostat is the first part of the sequence of operations for the gas furnace.
2
Control Board Initiates
The thermostat completes a primary circuit for heating. This completion of the heating circuit in the gas furnace sequence of operation is a signal. A signal for the gas furnace control board to put everything into motion.
3
Induced Draft Motor Turns On
The induced draft or forced draft motor engages. Some furnaces have either a forced draft motor, and others have an induced draft motor. It depends on the engineering. The difference being the forced draft blower blows air through the heat exchanger(s). The induced draft motor pulls air through the heat exchanger(s).
4
Safety Circuit Check
Above all, safety is vital. The gas furnace control board checks the safety circuit to ensure all the safeties are closed.
5
Ignition Process Begins
After safeties are confirmed to be good, the control board sends a signal to start the ignition process. Depending on the type of electronic ignition gas furnace, the source of ignition starts a trial for ignition. You could have hot surface ignition, direct spark, intermittent pilot, or possibly some other ignition. See our article for electronic ignition gas furnace types.
6
Flame Proving
The trial for ignition includes a flame proving to ensure there is, in fact, a flame. That proves the gas is being consumed and not spewing into the environment. In that case, with no flame, the furnace would create an explosion hazard. Most manufacturers use the flame rectification method to ensure the flame is burning. A flame sensor that touches the flames when the burner ignites takes care of this issue. A single wire runs from the flame sensor to the ignition control board or module.
7
Main Burners Fire
Once the control board is satisfied that the flame is proven burning, either it opens the main valve. The intermittent pilot lights the main burners. In the case of direct ignition, the main burner is already burning, and the heat exchanger is heating up. The heat exchanger is getting ready for the next part of the gas furnace sequence of operation.
8
Blower Control Initiates
The next step depends on the manufacturer of the control board. Blower control is either on a timer or a temperature sensor. That controls the time when the blower turns on. The reason for this is that the heat exchanger needs to warm up before the blower turns on. That is so warm or hot air is delivered throughout the supply ducts.
9
Thermostat Satisfies Setpoint
Furthermore, the next step in the gas furnace sequence of operation is the thermostat is satisfied and shutting everything down. This process happens with a small delay in the blower shutting down. That allows heat to be dissipated from the heat exchanger. The burners shut off immediately once the thermostat is satisfied. The blower usually continues on a timer. However, some systems do control the blower by the temperature in the heat exchanger.
10
Shutdown Sequence | Electronic Ignition Gas Furnace Problems and Troubleshooting
Lastly, the blower shuts down, and everything is off and waiting for the next time the thermostat calls for heat.
Standing Pilot Gas Furnace Sequence of Operation can be found here. The standing pilot sequence of operation is different than the sequence for the electronic ignition gas furnace.
Electronic Ignition Gas Furnace Problems Troubleshooting
In any case, many things can happen in that furnace sequence of operation that can prevent the gas furnace from providing heat. Probably the first thing that can happen that prevents the furnace from starting is the failure of the draft motor. In that case, the power to the motor, which usually originates from the control board should be checked. If that is okay, then the motor itself needs to be checked.
For instance, a bad inducer or forced draft motor prevents the pressure switch from closing. The pressure switch is in the safety circuit. If the safety circuit is not complete, then the control board stops the process of the gas furnace igniting. The gas furnace problem with the motor or the pressure switch needs to be corrected and corrected before proceeding any further in the process of fixing the gas furnace problem.
Furthermore, another issue that can occur with the draft motor is the blower wheel. If the blower wheel is bad and not moving air, then it needs to be repaired. Additionally, some manufacturers use an eighth-inch rubber or plastic hose to check the pressure for the pressure switch. If the hose is disconnected or dry rotted, it needs to be repaired or fixed.
Manual Reset Limit Switch
Safety Switches
Electronic Ignition Gas Furnace Problems Troubleshooting
Another furnace problem to troubleshoot that is related to this is one of the safety switches being open. The pressure switch is a safety switch. However, other safety switches include limit switches that can trip. Switches trip either because the switch is faulty and needs to be replaced or a problem. A problem that is causing too much heat to build up and causing the safety limit to open. It opens to prevent damage from excessive heat build-up. Additionally, safety switches are critical and prevent catastrophe.
Lastly, you should check all limit switches in a gas furnace problem with a limit switch. Or a gas furnace problem in the safety circuit. A bad blower, dirty filter, collapsed ductwork, the plugged-up flue can cause the limit switches to open. All the gas furnace problems need to check out with proper troubleshooting techniques. All problems are resolved before the furnace is returned to operation.
Flame Sensor
Electronic Ignition Gas Furnace Problems Troubleshooting
Furthermore, the next most common problem for furnace troubleshooting is the flame sensor or flame rectifier. This problem can be observed when the intermittent pilot or the direct ignition of the main burner ignites and then extinguish itself right away. The fire in the burners or pilot extinguishes after a slight delay. There is a flame. However, the flame sensor fails to recognize the flame.
In this case, the flame sensor is probably fouled or dirty and needs to be lightly sanded to remove the invisible problem that gives us this gas furnace problem. Proper furnace troubleshooting techniques can solve this issue.
Safety Limit Switch
Additional Common Issues
Electronic Ignition Gas Furnace Problems Troubleshooting
Additionally, another common problem with electronic ignition gas furnaces is that the igniter fails for whatever reason. In this case, it is prudent to check the ignition wire and the control board or control module where the spark originates. Do this to make sure it is activating the proper voltage to make the spark. Of course, this applies to spark ignition electronic ignition gas furnaces—however, not too hot surface igniters, which is a different animal altogether.
Of course, the same applies to a hot surface ignition gas furnace as you check the voltage output from the control module or furnace control board, which on most gas furnaces, the voltage is 120 volts, with a few being rated at 240 volts. Another exception is the Honeywell smart valve, which is 24 volts to the small hot surface igniter located at the pilot light.
Hot Surface Ignition
Hot Surface Igniter - it will glow red hot when in the ignition mode
Furthermore, on the hot surface ignition gas furnaces, if the voltage output is there to the igniter, the igniter may be bad. To check the igniter, you can Ohm it to make sure it has resistance. If no resistance is read (open circuit), then the igniter is broken or cracked and needs to be replaced.
It is also essential that any gas furnace ignition system has good ground. The module needs good ground to the control board or control module. That ensures the 24 volts system is not a floating 24 volts. That means the 24 volts cannot float from one leg to the other. When it has a proper ground, the control voltage, the 24 volts, does not float. Instead, you have the 24 volts on a single leg. That is what you need on the electronic ignition gas furnace controls.
Conclusion Electronic Ignition Gas Furnace Problems Troubleshooting
Other gas furnace problems exist; however, these are the most common ones that can look for when troubleshooting. Later we’ll add some more gas furnace problems in this article.
Additional Frequently Asked Questions from our readers:
How do I know if my furnace ignitor is bad?
This depends on what type of electronic ignition you have in your furnace. Probably the most common ignition failure is:
- the flame sensor is fouled. This will prevent the furnace from providing heat. It is a safety feature for the furnace. Clean it but be very careful cleaning it. Very fine-grit sandpaper or a wire brush will do it.
- The next most common ignition problem is a cracked hot surface ignitor. Replace it.
- The next problem is a wildcard. Check any furnace flash codes if the furnace is so equipped.
Can I light the pilot manually if the furnace is electronic ignition?
The short answer is no. See another article we wrote on this topic. Lighting a pilot for electronic ignition?
What causes furnace ignition failure?
The answer to that is extensively explored in this article along with other articles in our gas furnace troubleshooting category.
The electronic ignition is not doing anything except flashing a light. What is the problem?
It is likely in the lockout mode as discussed in this article. Wait at least 30 minutes and then reset it by turning the power off to the furnace. Wait a few minutes and restore the power. It will go through its cycle and if something is incorrect it will shut down again. Many of these ignition control boards or modules will flash a code. To learn about gas furnace ignition control flash codes see this article.
Electronic Ignition Gas Furnace Problems Troubleshooting
Electronic Ignition Gas Furnace Problems Troubleshooting
I have a carrier 58 series 66,000 btu ( -070 model) gas furnace with heated wire type ignitor that would light and was giving code 12 so cleaned the flame sensor , checked pressure switch and all connections . The ignitor would glow but no gas would flow so I rapped on the solenoid area of the gas valve pretty hard with the handle of a large screwdriver which worked . I would say the solenoid is faulty but I was not getting a 24V AC reading during prior check . Noted the ground wire to the gas valve is shared between the frame and to the circuit board so as afterthought am wondering if the valve uses DC which is why I did not read voltage as AC . Or was it the flame sensor contamination that prevented the circuit board from energizing the solenoid ? Code 12 went away , too.
Not likely to use DC voltage to the gas valve. If you read the specs for the gas valve it likely says 24 VAC. It is possible the ground was not connected properly or you could also have a gas valve that is sticking. Gas has moisture in it and if the moisture gets too cold it will freeze inside the valve. Is this unit in an unconditioned space/area?
We have a Day & Night furnace, installed late 80s. Been having problems with having the furnace kicking on. I have replaced the circut board and the safety button already. The T-stat goes into starting mode but the furnace will not start. If I take the top panel/door off and depress the safety button with my finger, it starts right up. Pilot lights, burners ignite and the fan kicks in. When I replace the panel I can hear it go into the starting mode. All is fine and the furnace will continue to cycle off and on for the duration of the scheduled time period without any issues. When it comes time to restart the next time period, same problem. I have to take the panel off and go through the same sequence by manually pressing the safety button. Any suggestions? Thank you
Not sure exactly which safety switch you are talking about? The panel switch or another safety switch? If you could take a photo of it and upload it I can see what you are talking about and help you. Our uploader can be found in the menu on the right or in the drop down menu above under Website Stuff/Share Your Photos. Thanks and I look forward to helping you.
It’s probably the panel switch. I didn’t know what to call it. Looks like a bullet, about 1-1/2″ long, is held in/depressed by the panel when the panel is installed. it must be depressed in order for the furnace to function.
Okay, then you will likely have to go through a Day & Night dealer to get a new switch for that furnace. I tried looking for one online but found nothing. Day & Night is also owned by the same company that makes Carrier and Bryant so if you cannot find a Day & Night dealer in your area then try a Carrier or Bryant dealer.
I’ve already replaced it with a Coleman Evcon S1-02435738000 Furnace Door Switch, after, I had replaced the circut board HH84AA020.
Sorry, I can’t offer any help except to say call a pro and get the right switch designed for that furnace. There is a work around but a pro needs to take care of it.
i work at a hotel and the boiler igniter crapped out again,it seems to go every year,why?it’s a Laars part #2400-286
Perhaps environmental problem……..corrosive environment? Not exactly sure without looking at it.
Having issues with my furnace recently. It uses the very common Honeywell controls, the Q345 pilot burner/sensor and the S8600m Control module. When it fires up, Draft motor comes on, Spark fires, and Pilot lights. But literally less than a second after Pilot lights, it goes right back out and starts this process over every 5 seconds. Pilot and Spark seem both strong and normal, but the main burner never ends up igniting.
Could this be due more to the Flame Sensor, OR the Control module. I tried checking the Milliamps through the sensor circuit, but I think it reads about 3 mA, but the reading is only displayed a fraction of a second, due to how short of a time the Pilot is actually lit.
these systems use microamps and not milliamps. Likely a bad sensor.
i own an air flo gas furnace that will only come on if power is turned off then on again. blower motor comes on igniter glows valve clicks but burners won’t light unless i lightly tap black pipe gas jets are mounted on…the led in electronic section doesn’t blink at all…any ideas?
Call an HVAC contractor
I have a Coleman furnace. Just moved into this house so I’m not truly familiar with everything yet. Since the furnace has started running this winter I have had a fine dusting of white dust all over the house each morning that I have noticed. I have had an inspector come and inspect the heat exchanger for leaks and he did not find any. Have left the door to the furnace open so it would not be deprived of air to burn. Still a white dust all over everything. Do you have any ideas as to why this might be happening?
likely you have leaky ductwork on the return side. That will suck up dust and fine particles like a vacuum cleaner (as the return side of the duct work is a negative pressure). If the return leaks it is also very likely that the supply side also leaks. It either needs to be replaced or completely redone where the insulation is stripped off and all the seams and joints sealed with duct sealer and then re-wrapped with insulation. The problem is also very bad for your evaporator coil as all that dust will collect in the coil and plug it up making inefficient and cause a failure of your system after it gets completely plugged.
I have a Honeywell sv9501 smart valve. HSI will not glow…there is 24v to ground on both of the wires when measured individually…but no voltage when checking voltage between wires…is this a floating voltage issue? All connections seem tight…ignitor checks ok…power to gas valve is ok. Kind of stuck where to look next,
replace the valve……..???
Just installed a new Goodman GMSS92. Unit is at 7000 feet, and unit is rated for this altitude. When unit calls for heat, the ID fan starts, igniter glows, then the gas flows, but the burners sputter (as tho the gas was quickly turned on and off), then gas does not flow. The blowers work fine. The furnace will occasionally light up OK, but shuts off before temp setting is reached.
Check to make sure manifold pressure is correct (as necessary for the altitude) and that there are no blockages in gas line at all. Other than that you probably need to call in a factory rep to check it out.
This gama furnace runs good once it come on spark module replaced flame sensor replace gas valve its getting fire an gas but most of time it won’t light sometime it will on it on cold nights I stick grill sticker it light every time. just keep me up. reach temp cut off have light it up again sometime it light on it on you never know when
Best to call a technician rather than doing it the way you are doing it.
My Arcoaire furnace cycles and ignites, but every other cycle or two it tries to ignite the gas and it ignites, but the force of the ignition/combustion extinguishes the flame causing it to shut down the gas valve, run the exhaust and clear the gas, cycle down then start the cycle all over again usually resulting in a proper ignition on the second try. What causes this? The frequency of this has increased this cold season. Thanks in advance.
sounds like either the spark is weak or its too far away from the gas when the gas comes out of the main burners. Call a pro to have them look at it.
Very informative article. My HVAC central unit is having some trouble turning the heater on. It seems like the pilot won’t turn on. It has an automatic intermittent spark ignition pilot. I checked the holes on the pilot and they are clear. The flame sensor seems to be loose from the ceramic handle, the bar turns can turn, could this be the cause? the igniter seems to be working, at night I can see the sparks. The blower motor is starting to fail, it became noisy, seems like the bearings are bad, it still turns on tho, could this be the cause? Why won’t the pilot turn on at all, bad valves? bad ignition control module? thanks.
There is really no way to tell without having a professional look at it. If the blower is making noise it could be apart of the problem. Again without looking at it and testing a few things I can’t really tell. You will likely have to call in a pro to troubleshoot the issue.
I have a gas furnace. The heating and air service company has had to replace the ignitor many times, twice already this year (in January and it went out again several days ago in late October). I’ve been told that it might be due to a voltage problem. Any suggestions for further investigation of this problem?
Not sure how to answer this except to say if you have a voltage quality issue then it should be tested and something done to address the issue. There are meters you can purchase that will log everything with the electric power over a specified period of time. Some of these meters are expensive and you may want to hire an expert for this.
Hot Surface Ignitors can be very fragile and should not be touched with your fingers when they are installed. The oil from your fingers can cause issues with the materials in the ignitor. I’ve been told that is false and also told it is true so I err on the side of caution when installing them new.
Hello. Maybe you’ll have some insight or can point me in a direction. I replaced my ICM (rogers-white) last April when the diagnostic LEDs said it was dead. It’s been 4 months and it seems the replacement is dead. It worked fine (couple weeks in heat mode and then in cool mode this summer) There are no lights but there is a hum coming from the module. I’ve cut power, waited and reapplied the power and nothing. Is there something I should check for to see if there’s a condition that killed the two ICMs?
Thank you!
Make sure you have a good ground for the module, the equipment and the house. Other than that, make sure it is wired correctly. Modules are not that fragile.
I just replaced a boiler which has got a blower and a electronic white Rodgers gas valve. The blower turns on for few seconds then it stops for a second then it restarts and it repeats same cycle again. Is it that’s how it should work.I don’t know where I can get this advice.
I’m surmising you have a condensing boiler and if it was installed less then a year ago the installing contractor should of given you a one year warranty. I would call the installation contractor about this issue. It should be a warranty call and no charge unless there is some kind of negligence.
I have a York D1NA036N07206C on which I just replaced the gas valve(Honeywell smart) and the igniter because I was having intermittent
flame sensor or flame rectifier problem. Where the pilot or the direct ignition of the main burners will ignite and then extinguish itself right away after a slight delay. There is a flame however the flame sensor fails to recognize the flame. which didnot totally fix the problem until we positioned the exhaust motor pressure switch upside down, ??. Anyway today the unit decides to give out early this morning. It is running the exhaust motor, the blower motor, the pilot is on the igniter wire is red-orange.No flame up , no heat , just air thru the vents.
I never recommend making modifications to any appliance outside what the manufacturer suggests. It is a gas furnace that uses combustion to provide heat and making modifications such as you describe is potentially dangerous. Please call a trained technician. 99.9% percent of the time they can identify the problem right away and make the repair without changing several parts. It is very probable that the problem was not the gas valve but something else.
my blower motor isn’t working on automatic. The furnace ignites and when gets hot turns off. When blower motor is set to be on all the time-it works fine. What is the problem.
Sounds like a bad limit switch or a problem with the airflow. Make sure the filter is clean and you have good airflow. If you do then you need to call an HVAC company to check it out to make sure everything is safe and good.
I try to light my furnace, it clicks a few times nothing happens. Then goes into lockdown mode for one hour. Tried again same thing any ideas?
Electronic ignition system go into to lockout mode when there is a problem in the safety circuit. Anything safety related especially with a gas furnace needs to be checked out by a professional HVAC technician.
Igniter was replaced a month ago. The problem is my blower runs and igniter isnt working. Per my blinking lights, it states ignition locked out will retry 3 more times. So if I turned the furnace and thermostat off for 3 hours as instructed. After 3 hours, everything came back on. Happened a couple of times. What do I need to do?
Request an opinion:
Our gas company subcontractor relocated our gas meter and had to change/reroute gas piping in our basement. The furnace gas valve, closed for piping changes, was not open when I switched the thermostat to call for heat last night. Now the auto-ignition no longer functions. Question…What damage can be done in an ignition attempt without gas flow?
if they pressure tested the new line, which is required by code to make sure no leaks are in the new line, and if the did not isolated the gas valve from the high test pressure then damage could have occurred to the gas valve.
my tenant says when he turns on the tstat for heat, the furnace makes a loud explosion noise when it first fires up – any idea on what causes this… sounds like gas accumulating in the heat exchanger and igniting late ?? thx, Chris
@Chris
Yikes. Hopefully your tenant and structure survived the winter — loud ignition is a sign of problems! I would look at the following:
1) induced draft fan to see that it is pulling exhaust gasses
2) blocked exhaust/chimney flue
3) cleanliness of gas metering. Is the valve closing off. Put a sniffer on it, check for leaks.
4) hot surface ignitor. Clean? Working correctly? or if pilot light — even and adequate?
and check that heat exchanger for cracks (carbon monoxide risk)! explosive ignition induces large pressures on the unit it was never meant for, and can cause damage.