How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Brian HVAC Guy Your Own Question
Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 854
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
67988511
Type Your HVAC Question Here...
Brian HVAC Guy is online now
A new question is answered every 9 seconds

I have a Gibson gas furnace, 80+ or 90+ model ... about 12 -

Customer Question

I have a Gibson gas furnace, 80+ or 90+ model ... about 12 - 13 years old. I tried resetting the furnace. It will not light. Red light on circuit board gives 4 flashes, indicating "ignition failure (check ground)".
Submitted: 1 year ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 1 year ago.
Hi I'm Brian and I'm here to help! Let's get started... A little more info will be helpful. How did you try to reset your furnace? Also, if possible, the model number of the furnace would be really helpful. It should be located on a data plate on the inside cabinet face of the furnace after removing the blower panel.
Customer: replied 1 year ago.
I just tuned it off, also shut breaker off and back on again. Gibson, Model # ***** 120C - 20C.Fan comes on, can hear various clicking noises like it is trying to start things ... then fan stops after a few minutes, then got flashing light on circuit board (4 flashes, indicating "ignition failure (check ground)".)
Expert:  Brian HVAC Guy replied 1 year ago.
Ok thank you for clarifying that for me. Depending on the model and control board in your model furnace, that indicates all safeties are fine and ignition is called for by opening the gas valve then no flame is sensed. This can be caused by many things. Do you have any other gas appliances in your home? If so, are they operating properly? We need to make sure there is a proper gas supply to the furnace. That is the easiest way to tell. Also, when you say it doesn't light, do you mean there is NEVER any flame or it lights briefly then goes out?
Customer: replied 1 year ago.
Gas stove in kitchen works fine. I don't think it is lighting at all. I assume I would see it lit in small round window
Customer: replied 1 year ago.
... above electronics?
Customer: replied 1 year ago.
Not sure if this is anything ... there is a bunch of corrosion on clip where red wire connects at top. I took clip off and uses sandpaper to try and clean. (Top right of last image i sent)
Expert:  Brian HVAC Guy replied 1 year ago.
No, you probably wouldn't see it in the same window you see the flash code. You should hear the slight woosh when it lights though. Since we know you have gas supply, the most common cause for this is a failed Hot Surface Ignitor. It could also be a fouled flame sensor or at worst a faulty gas valve but with your symptoms, my first thought is the HSI. If you're comfortable removing the furnace panels you can look for corroded terminals or a fouled flame sensing rod which is located right at the burner nozzles in the burner section.Ah, just got your last post.. corrosion can certainly cause this kind of issue. You should remove power and clean any corroded terminals you can find. Especially where the furnace control board is mounted or grounded. That's why they refer to "bad ground" in the detail of 4 blink code.
Expert:  Brian HVAC Guy replied 1 year ago.
And if you attached any image(s), I didn't receive them :(
Customer: replied 1 year ago.
Trying to upload image again ...
Expert:  Brian HVAC Guy replied 1 year ago.
Ok thanks, ***** ***** one image that time. I'm reviewing it now...
Customer: replied 1 year ago.
The indicator light I am seeing is on the circuit board (left side of pic). Would I see flames in the small round window at the top of the pic? (not sure where things are on this furnace ... everything is covered)
Expert:  Brian HVAC Guy replied 1 year ago.
In your picture, in the little round inspection window at the top is where you would see flame if it were present. The spark plug looking connector with the red wire connected to it is your flame sensor. If there is corrosion there it could definitely cause a failed flame sense issue and give you the 4 blink code. The burner panel cover should come right off by removing the 3 or 6 screws attaching it (the panel with the round inspection window). That may give us more indication on what's going on but as I stated, I would suspect either the hot surface ignitor, the flame sensing rod or a corroded connection. Those are by far the most common causes of flame fail or fail to light conditions.
Customer: replied 1 year ago.
OK. I will remove the burner panel cover. The flame sensor is very corroded ... actually, the blade portion where the red wire slides on was rusted pretty badly. Again, I hit the "blade" with some sandpaper. Attached is a better shot, showing the corrosion.
Expert:  Brian HVAC Guy replied 1 year ago.
Yes that is quite corroded. if you remove the wire and remove the one screw holding the flame sensor in, you should be able to pull the entire flame sensor out and you can clean it with a wire brush and/or emery cloth or a Scotchbrite pad. The flame sensor is pretty hardy, the only care you need to take is to be careful not to crack the porcelain insulator. The probe coming out of the end of the insulator is what senses the flame and can be cleaned with emery cloth or the like as can the electrical connector both male and female. You should also clean the mounting surface of the flame sensor so it has a good physical connection to the burner box. That may solve your problem. When you remove the burner cover panel, you should also be able to see the hot surface ignitor. You can follow the wires up from the molex connector on the bottom left of the burner box to find it. Hot surface ignitors are very fragile once used and cannot be cleaned without damaging them. If you see that it is cracked or deformed in any way, it should be replaced.
Expert:  Brian HVAC Guy replied 1 year ago.
How did that go? Did we zero in on the issue yet?
Customer: replied 1 year ago.
I removed the flame sensor, but I don't have any of the items you listed to clean it. Got busy and could not get to the store. And I have not had a chance to remove the burner cover panel.
Expert:  Brian HVAC Guy replied 1 year ago.
Ok, very good then. Just let me know how I can help further and please remember to rate your session with me. You can come back any time for further help even after rating. I'll receive an email alert when you post a new reply. Thanks much for allowing me to help thus far! -Brian
Customer: replied 1 year ago.
Any tips on cleaning the female end of the electrical connector to the flame sensor?
Customer: replied 1 year ago.
Also, I just removed the 6 screws to remove the burner cover panel and it seems like there may be some kind of adhesive holding it in place. Should I still remove it? Does the adhesive need to be replaced?
Customer: replied 1 year ago.
I cleaned the flame sensor and replaced. Same problem. Not sure if I should "force" open the burner cover. Again, all screws are removed, but it does not want to move.
Expert:  Brian HVAC Guy replied 1 year ago.
Sorry for the long delay, I was away and forgot to log out. The female connector can be cleaned with isopropol alcohol or contact cleaner. That's about the only thing you can do with that style connector, especially since it's an insulated connector. As for the burner cover, you furnace may have a gasket for the burner cover, many don't and many don't even have cover over the burners. If the gasket doesn't remain intact during disassembly, it can be removed and high temperature RTV found at at Wal Mart or any auto parts store can be used as a gasket when reassembling. If you're not comfortable with that, it may be wise to call your heating tech out. The ignitor may be able to be serviced without pulling the cover off, I don't remember on that particular furnace, it's been a long while since I serviced it. -Brian
Customer: replied 1 year ago.
I don't have a problem removing the burner cover and installing a new gasket if that is what is necessary. I didn't want to open it if it was not supposed to be opened. Is there someone else there that knows if the ignitor can be serviced without removing the burner cover?
Expert:  Brian HVAC Guy replied 1 year ago.
I don't know if any of the other techs here will remember working on your particular model or not. From the looks of the replacement ignitor, it appears it could be attached either way that would either require or not require removing the burner cover panel. If you snap a picture that gives a perspective on the bottom of that burner panel cover it will be obvious whether the ignitor can be removed without removing the burner cover panel or not. If the ignitor wires simply go through a hole in the cover then you will have to remove the cover to access the ignitor. If there is a bracket screwed on right where the wires are then you should be able to remove the bracket screw(s) and the ignitor should come right out without removing the cover panel. The reason for the burner cover panel is that you have a furnace that can be either direct or non-direct vent. What this means is your furnace has the burner section cordoned off so the combustion air can be brought in from outside through a second pvc pipe (direct vent) OR your furnace is able to use the indoor air surrounding the furnace for combustion by just not connecting the second vent pipe (non-direct vent). In either case there will be an exhaust vent pipe and a connection for a intake vent pipe on the top of the furnace and if you have a non-direct or direct vent system, you will have one or two vent pipes respectively. That is why your burner assembly has a cover over it, it's not a hugely critical seal especially if you don't have an intake vent pipe connected to it from outside. The burner cover box is in a negative pressure. With all that said, it's not a huge deal to take that cover off and the gasket seal is not that critical. Feel free to take it off and inspect the condition of your burner/nozzle assembly. There are screws along the bottom horizontal edges of that cover that need to come off as well. Now just to be sure we are talking about the same cover, I referring to the one at the top of the furnace where the flame sensor goes through. Not the cover below that which is the collector plate cover. That cover should not be removed unless your heat exchanger needs to be cleaned. The seal on that cover IS important! Let me know how I can help further. Thanks,Brian
Customer: replied 1 year ago.
Hi,Can you take a look at the attached pic? Is the top left with the brown wires the ignitor (I assume)?Thanks,
John
Customer: replied 1 year ago.
I removed it (see attached). Assume it needs to be replaced?
Expert:  Brian HVAC Guy replied 1 year ago.
Hi again. I'm sorry for the very late response, I haven't been able to get online until now. Yes indeed, that ignitor has failed and is likely the root of your problem. If you replace it (if you haven't already) I would suspect your furnace should be good-to-go! When replacing a hot surface ignitor, be careful not to touch the heating element, the oils on your hands will burn into it and it will fail prematurely. Thanks much,Brian
Expert:  Brian HVAC Guy replied 1 year ago.
Also, for your convenience Click Here for a manual for your model furnace. :)

Related HVAC Questions