Carrier Furnace quits working (14 error)


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Old 04-02-10, 11:15 AM
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Carrier Furnace quits working (14 error)

This past winter season my 1997 carrier furnace (80% efficiency, don't recall the exact model) started to quit working occasionally. It started happening maybe once a month, then once a week and now it's starting to get really bad, I sometimes have to reset (power off for a minute, power on) it several times a night. The furnace always appears to start just fine, then the flame starts, and a few second after the flame started (which looks just normal) it shuts it off. This repeats two or three times and then it shuts itself off entirely with the error code 14. I doubt that the temperature sensor is to blame, although I will try and clean it today, but it seems like it doesn't fix the problem permanently for most people. I also doubt that the circuit board is fried. What could be wrong here? I'm getting quite frustrated with this. The thermostat appears to be fine, I can hear it click and the furnace attempts to start, but later fails. And I can see on the thermostat that it's calling for heat, but since the furnace shut itself off, nothing happens and the house just gets colder and colder. I do have a multimeter, but I don't know much about electricity so I don't really know what/how I could test to get a clue.

Or should I just bite the bullet and get the furnace replaced? I don't really want to spend hundreds of dollars for replacing all kinds of parts, or even have a HVAC person inspect it (they rarely ever find the root of the problem).
 
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Old 04-02-10, 11:39 AM
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Usually you will find the diagnostic codes posted on the furnace --- 1-4 is commonly an ignition lockout for flame failure, but check that to see if that's the case for your furnaqce.

You need to post the model of the furnace, which can be obtained on the furnace rating plate, found in the burner compartment of the furnace.

You need to make a point of finding an honest and competent furnace repairman to service your furnace when needed. The idea of replacing the furnace when something quits is ridiculous, although the number of dishonest or incompetent repairman out there gives your sentiments a degree of reasonableness.

Check with friends, neighbors and relatives to locate repaimen who have treated them well, and make a note of their service before you need it.


It may well be that with this diagnostic code, the flame sensor needs cleaning. The flame sensor is on the opposite side of the furnace compartment from the hot surface ignitor that glows white hot to light the gas.

The flame sensor is a short rod sticking up into the flames with a single wire coming out the bottom and going to the ignition control/circuit board. Clean it with a wire brush or fine sandpaper. You don't need to cut into the metal to clean off the oxides.

It commonly gets covered with invisible oxides that prevent it from working.
 
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Old 04-02-10, 11:59 AM
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Thanks for the quick reply. Yes error code 14 is ignition lock out. I'll try and clean the flame sensor when I get home and see if it makes a difference. I know it's ridiculous to replace the furnace just because it has a small issue, however having done a lot of searching on the net for this same issue it seems like having a HVAC person come to diagnose never fixed the issue for anybody. It seems like they usually get it to work again (I can do that myself, too) and then hours/days/weeks later the same problem occurs again. I've read so many posts where people wasted lots of money for repairmen to come just to find the furnace working, or they just get it back to working without fixing the problem. That's why I thought that maybe replacing the entire unit makes sense. I don't have much electrical knowledge, so I don't really know how to diagnose bad parts, but I do know enough to replace boards or solder to replace bad parts.
 
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Old 04-05-10, 01:08 PM
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Cleaning the temperature sensor with sand paper appears to have fixed the problem. Thanks again.
 
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Old 04-06-10, 06:19 AM
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Furnace Problem

It sounds to me like your flame sensor is going. Commonly they get carboned up and stop reading properly. Just take the flame sensor out and lightly file off the residue build up and throw it back in.
 
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Old 04-06-10, 07:09 AM
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That's pretty much what I did. Except that I didn't remove it as it seemed like a little difficult to get out. Not much space there to work, and I didn't want to deal with disassembling a lot.

Originally Posted by MzFixit View Post
It sounds to me like your flame sensor is going. Commonly they get carboned up and stop reading properly. Just take the flame sensor out and lightly file off the residue build up and throw it back in.
 
 

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