Carrier Furnace LED Codes - where do I find their meaning?

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Old 02-20-11, 08:51 AM
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Carrier Furnace LED Codes - where do I find their meaning?

I have a Carrier Gas Furnace 58MXA100-20 that isn't working.
After reset, it's LED code blinks 1short - 2long for a while then 2short - 3long.
The manual on Carrier's website does not list the codes or meanings.

Where do I find the tech document that lists them? Or if not that ... anyone know what my 2 codes are?

Thanks for any help.
 
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Old 02-20-11, 09:49 AM
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The 1-2 code is displayed when the 120 VAC power is turned on while the themostat is calling for heat. The fan is switched on for 90 seconds during this cycle.


The 2-1 code is displayed when the ignition control module has turned on the main burner gas but failed to detect that the burners have lit.

Do you see the hot surface ignitor glowing white hot to light the burners? Are the burners lighting for 3-5 seconds and shutting off?
 
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Old 02-20-11, 10:13 AM
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You're right - the 1-2 code blinks while the blower fan runs immediately after the reset.

Then fan stops and the 2-3 code blinks (not 2-1). No igniter glow or draft fan or noise - just crickets for several minutes.

I had a backup in the condensate trap because it went to a tube that led outside and froze there. I cleared the frozen line and it drained. There is some water on the floor and in the base of the unit.
 
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Old 02-20-11, 11:16 AM
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http://www.docs.hvacpartners.com/idc.../58mxa-6sm.pdf

Are you getting 120VAC to the vent motor after code 12 stops?
 
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Old 02-20-11, 11:32 AM
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The 2-3 code is signaling that the pressure switch is stuck closed.


When the inducer motor is off, the pressure switch should be open. When the inducer motor comes up to speed, it should close.

Use a multimeter to check the voltage at the pressure switch to verify if the pressure switch is indeed staying closed when the inducer motor is off.
 
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Old 02-20-11, 02:36 PM
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23 PRESSURE SWITCH WILL
NOT OPEN - Check for:
Disconnected or obstructed
pressure tubing.
Defective pressure switch.

If the pressure switch measures closed when the inducer is not running, you might remove the hoses connecting it to the furnace and test it again.
 
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Old 02-20-11, 08:00 PM
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I may be over my head. I don't know what the "pressure switch" is or where it is sensing pressure. Same with an "inducer motor". For some reason it's now working - perhaps the water had gotten into something and is now dried out or I relieved some pressure or block somewhere while looking closer for more water backed up in various tubes - I disconnected and reconnected several.

Thanks for the help - I'll see if I can figure out your clues and if it happens again I'll have to call someone who has been inside a furnace before.
 
 

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