Furnace blowing cold air: igniter only 5 volts

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Old 01-28-19, 05:55 PM
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Furnace blowing cold air: igniter only 5 volts

My central heater for my condo started blowing cold air. I had a guy come out and we went on the roof and he said the burners weren't getting a spark. He tested the igniter with his multimeter and determined that the igniter was defective. He said that he could not find the part since the heater is so old (about 35 years). So he gave me a quote for a whole new unit at about $6,500. Anyhow I went online and found the part for about $75. When I got it, I installed it but still there is no spark. With the heater running I tested the voltage of the igniter. Here is the igniter I have although the replacement even though it has the same model number does not have the spade connectors. It just has two wires. https://controlscentral.com/eCatalog...Rodgers,%20Inc.

I tested voltage from both of the two points to ground and measured only about 5-6 volts. It should be 25 volts right? Any idea what I'm doing wrong or what the problem would be?

Thanks!
Don
 
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Old 01-28-19, 07:03 PM
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Don't measure to ground, measure on the terminals, should see 125 VAC.
 
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Old 01-29-19, 12:57 PM
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Thanks, I will try that today. If the voltage is correct then what else could be causing the igniter to fail to spark?
 
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Old 01-29-19, 05:28 PM
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Welcome to the forums.

Some confusion here Don. The part you linked to.... 5059A21.... is shown as a 120vAC spark re-ignition module. If your furnace supplies 24vAC to it...... it will never work.

You need to verify what you have..... a 24vAC or 120vAC system there.
If you don't know.... maybe try posting the wiring diagram for us....... How-to-insert-pictures
 
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Old 01-30-19, 11:58 AM
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Pete, good catch! I didn't notice that. I just checked the model number which is the same which is strange. I'm waiting to here from the supply house to get the correct unit. Thanks!
 
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Old 02-06-19, 06:09 PM
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Okay, so I received the new igniter with the correct specs. 24Volts, 0.030 Amps, 60Hz. The part number is 5059-23 and not 5059-21 like the original which I could not find. I looked online and apparently these two igniters can be used interchangeably. I connected it and immediately got a spark once I turned it on. The burners ignited and I had heat again! However sometimes the heater will still blow cold air continually even if I turn the thermostat way up. I'm guessing there are times when either the burners don't ignite or they don't get gas. What should I check next? Perhaps the original igniter burned out continually trying to ignite the burners? Any help would be appreciated!
 
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Old 02-06-19, 06:58 PM
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Update: When I turn the thermostat from OFF to HEAT the unit turns on and hot air starts to flow. Once the unit reaches the set temperature it turns off as you would expect. Then when the temp drops and the thermostat turns the heat back on it blows only cold. In order to get it to blow hot again I have to turn the unit from HEAT to OFF and then wait for the blower to stop. After this 1-minute break I can turn the unit back to HEAT and again it will blow hot air. Does this mean the thermostat is at fault?
 
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Old 02-06-19, 09:16 PM
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Do you have a picture of the wiring diagram?

what is the model of this unit and the manufacturer?
 
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Old 02-06-19, 09:39 PM
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However sometimes the heater will still blow cold air continually even if I turn the thermostat way up. I'm guessing there are times when either the burners don't ignite or they don't get gas.
You need to go out there and see what's doing when it should be heating.

Is the spark running but no ignition ?
No spark and no ignition ?
 
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Old 02-06-19, 10:40 PM
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Moory, I'm not sure of the model. It's so old and has been painted over. I can take more photos in the morning but here is one I took of the inside before I replaced the igniter. https://www.dropbox.com/s/v2jxw9p2ns...57.43.jpg?dl=0

Pete, great questions. I will check in the morning and let you know. Thanks.
 
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Old 02-08-19, 12:49 PM
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So somehow, without doing anything, everything seems to be working fine. The only thing I can think of that could have been causing some issues was that the recent rains caused some water buildup inside the unit. But in any event thanks for all the response and help! I sincerely appreciate it!
 
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Old 02-08-19, 06:34 PM
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You have the magic touch. If it goes out again..... stop back.
 
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Old 02-08-19, 11:09 PM
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it sounds like your prayers finally saved you.... the furnace is working again. Helelojia 🙂🙂🙂.
 
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Old 02-11-19, 10:59 AM
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It is strange! Thanks for all the assistance!
 
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Old 02-18-19, 12:59 PM
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Alright, so as you might have figured the problem has resurfaced. It definitely has a problem when it rains where the flame won't ignite. There is some water build up on the bottom of the unit but nothing so much that seems like it would be affecting the burners to ignite. However after taking a hair dryer in the general area the burners do then catch. Also I noticed that when the burners are lit I still hear the igniter sparking once or twice every 10-15 seconds. Any insight on anything I mentioned? Is there a pilot light burner that needs to be cleaned? Thanks!
 
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Old 02-18-19, 01:14 PM
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We don't know if there's a pilot light. You weren't able to post a model number.
Does the spark ignition light a pilot flame or is it direct ignition ?
If you hear it sparking after the flame is lit.... it's not registering the flame properly.
 
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Old 02-18-19, 01:42 PM
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Thanks Pete. I think there is a pilot light. I can check more closely when I go up again. What might be some reasons that the flame is not being registered properly?
 
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Old 02-18-19, 03:24 PM
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A typical problem with an intermittent pilot system is a dirty pilot orifice.
A full flame is required for ignition and to satisfy the spark module.
 
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Old 02-27-19, 01:03 PM
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I cleaned out the orifice of the pilot light the other day using this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

That solved the problem of the heater not lighting at times. Now the only problem left is that the igniter still sparks occasionally when the burners are lit. What should I test? Thanks!
 
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