Troubleshooting Gas Furnace


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Old 03-03-13, 09:22 AM
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Troubleshooting Gas Furnace

Hey everyone!

I am trying to figure out what might be up with my gas furnace. The symptoms are a little strange. So far, I swapped out the thermostat to verify it was not the cause.

Heres what happens:
I turn the thermostat up, the furnace turns on and heats up the home. When the temperature drops again, there is a small motor that turns on, but the ignighter doesnt ever light and heat the furnace up again. Sounds like the ignighter right? Well, thats on order... But here is the weird part. I have kind of let this go for about 2 months and just do a "trick". Keep in mind it works absolutely 100% of the time and ive been doing this several times every day. I walk back over to the thermostat, turn the temperature down, to below the current room temperature which turns off that little motor. Then I turn it back up again to the desired temp. Then the motor turns back on, I hear the "click" of the ignighter and it gets hot and I hear everything kick back on, and alas, have heat. I dont know why 100% of the time this works. I can say the issue came on gradually and now I dont think it ever maintains temperature without the trick. If it were the ignighter, wouldnt it fail at least a percentage of the time with the trick? I started thinking about it where maybe something isnt turning off and by turning down the temp, maybe I am somehow resetting something that happens in the chain of events from the small motor turning on and the ignighter lighting. Its sending the signal to the heater as the motor will turn on. Another thing to note, is that motor DOES turn off after it reaches the desired temperature. I am absolutely novice with heaters. What other components could fall between that motor and the ignighter lighting? Does this stand out to anyone as something they have come across? I had some heater guys that I paid 150 bucks tell me in December that nothing is wrong with my heater. Obviously, I dont want to keep paying for them to tell me that.

- A single woman with very limited knowledge trying to troubleshoot her heater :-)
 
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Old 03-03-13, 10:14 AM
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Your problem is not the igniter. The control system is going into a "soft" lockout at the end of the firing cycle or the beginning of the next cycle. Turning the thermostat down resets this soft lockout. You need to determine what is causing the lockout and concentrate on that part.

Does this furnace have a diagnostic LED that flashes in a particular sequence to indicate faults? If so, there should be a sheet somewhere on the boiler to interpret the flash code to help pinpoint the problem. This sheet is often pasted inside the blower compartment door.

Give us the make and full model number of the furnace and someone should be able to help.
 
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Old 03-03-13, 10:34 AM
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Interesting. I identified the control box and even see where it gives a couple warnings on "lockouts" :-). There is an LED. While looking for the model, the heater clicked on. I saw it worked to light the ignighter this time (so not failing 100% of the time at least). The LED blinked Red one time and instantly after I heard the click. The model of the control box itself is "White Rogers- Emerson Electric - Model S0E47-060. Those Zeros, look like zeros, but could be "o"s.

I dont see any documentation for figuring out the LEDs but maybe can find something on line. I have to say I never noticed the LED lighting up. Should I assume this will only happen when the control box initiates start up/turn off?


The heater itself is a American Standard. 1988. Model TUC0608936A0

The outside door says Trane Super Efficiency Gas Furnace XL 90.

Thanks for your input so far :-)
 
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Old 03-03-13, 10:46 AM
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Oh I did find a wiring diagram on the bottom door by what seems like it would be called a blower. ha. (large internal fan for pushing out the air?) It shows how everything should be wired up, and I see the control box on there but nothing about the LEDs.
 
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Old 03-03-13, 02:40 PM
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On the control it lists what the code is. It is likely a flame sensor issue. Remove and clean the flame sensor with steel wool.

it is a 50E47-060
 
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Old 03-03-13, 06:58 PM
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Ya know, the fellow looking at my heater did exactly that in December when he came out to inspect things and I did not notice an improvement, however, I would not object to trying it again if you feel a second time around could prove helpful.
 
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Old 03-03-13, 07:18 PM
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Well, it would be nice to know what code you are getting for sure............
 
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Old 03-04-13, 05:24 AM
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This morning I checked it when I woke up cold and it is solid red. No flashes or beeps. Just red. I took a look on the control box for codes but didnt see any there either unfortunately.
 
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Old 03-04-13, 05:57 AM
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Solid red is replace control I believe.
 
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Old 03-05-13, 04:11 AM
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Thanks for the help.... hmm. Do you mean as if the control box itself needs to be replaced?
 
 

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