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Evcon furnace trouble shooting model DGAT070BDC - ignition module or gas valve

I have checked a couple parts already and need some direction as to the place to look. I have an evcon furnace model DGAT070BDC. I was having trouble with my booster motor running constantly even after the finish of a heating cycle so I took both limit switches and the booster relay in to a furnace place to have them checked. They said my relay was bad so I purchased a new one. They checked my high limits both were good. I put it back together but when I started the process I had not flipped the breaker off yet and had some arching on one of the relay wires. I then finished assembly and now my furnace does not light and the inducer still continues to run. I did take the inducer -booster motor in for a bench test and the cetrifugal switch is fuctioning properly. Not to many parts left to check and could use some help. Im guessing its not the ignitor when I put the testor to either wire it is not energized during the first 5 min. Im thinking it must be an ingition modual or gas valve? Hope you can help. Thanks Ted

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Manage My Life
Sounds like you have 120 to most areas of the furnace and more than likely 24VAC. You said when you turned the furnace on to heat the inducer motor came on. That's good. You would then need to check to see if the limit switches are closed. My wiring diagram shows you have a manual reset main limit and a temperature reset limit to go along with the fan switch that has the two orange wires going to it. Make sure those two switches are closed. If they are, you should be getting 90-110VAC to the hot surface ignitor. You can check for that voltage at the IGN terminals of the module.



If you get voltage to the ignitor but it does not glow, the ignitor is bad. If you do not have voltage going to the ignitor, check for 120VAC at the L1 terminal of the module. If voltage is coming in on the L1 but not to the ignitor. Replace the module.



If the ignitor glows, check for 24VAC to the gas valve. If there is 24VAC to the gas valve, but the gas valve is not opening after the ignitor heated up, replace the gas valve.
by Manage My Life
November 24th, 2012
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i just checked the a/c relay and got 27v at yellow and white wire, 120v at black wire, 0 at the light brown wire
by Manage My Life
November 23rd, 2012
Answered in 21 hours
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checking the a/c relay i have 27v at white and yellow wire, 120v at black wire, and 0 at red wire.
by Manage My Life
November 23rd, 2012
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just checked from white common on transformer to solenoid got 26.3 to brown wire, 27 v to yellow pair of wires on solenoid. Just checked from white common to fan relay and got 126v at 2 and 4 position, got 27v at 3 position/yellow wires, and .1 at the blue wire/position 1
by Manage My Life
November 23rd, 2012
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Were does the circuit start and how do I trace it. I started with my volt meter and put the black -common lead to the white wire coming into the transformer. I then checked with the red lead the connections on the transformer I got 26.8 v on the yellow wire, .1 on the red wire, 125.6 on the black wire,
by Manage My Life
November 23rd, 2012
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I do have the manual that came with the furnace which has the wiring diagram as well. The combustion motor is coming on and I have checked the fan relay and have 125 volts at 2 and 4 when I turn on the furnace. I pulled the wires and checked it is open at 2&4 and closed at 1&3 (it is reading ..071 on 2K setting)
by Manage My Life
November 23rd, 2012
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For some reason, the wiring diagram didn't attach. Let's try this again.
by Manage My Life
November 23rd, 2012
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As long as 1,3 is a 24VAC contact and 2,4 are 120VAC you're fine. Pins 2 and 4 should be normally open and close when 1,3 get 24VAC. That will bring on the combustion motor.
by Manage My Life
November 23rd, 2012
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Wiring looks ok aside from one wire, but I assume that color faded over the years. I attached a wiring diagram because I can't see the honeywell module or the motor. Make sure each one is wired correctly. If they all are then it's time to go hunting for the missing 24VAC which would require a multimeter.



It's possible that Honeywell module is done, but the only way to be sure is through a series of voltage checks.



Voltage is being lost somewhere and the only way to find it is by tracing through the circuit.
by Manage My Life
November 23rd, 2012
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I did pick up a new relay from a local furnace place as well. it is a white rodgers not exactly the same part number but they told me it would work. It has the numbers 1&3 for the coil end and 2&4 where power comes in same as old one.
by Manage My Life
November 23rd, 2012
Answered in 19 hours
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Thanks for your response. I did have the inducer bench tested which may have loosened a stuck centrifugal switch. I did take notes on the wires on the relay so I know exactly how they were on the old relay so I am putting that back on and will send that picture on as well.
by Manage My Life
November 23rd, 2012
Answered in 19 hours
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Manage My Life
Your original problem was more than likely a stuck combustion motor relay which it seems that you replaced? Or did you replace the A/C relay?

The inducer is trying to tell you that something is wrong. That problem is either you wired something wrong, or something was shorted when you tried to rewire the system while it is hot.

I can't determine if it is wired from because there are wires hanging around the combustion relay unconnected.

I wouldn't do anything else to your furnace until you are sure you have it wired properly.
by Manage My Life
November 23rd, 2012
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Good morning.... I can appreciate your concern with winter coming on... I will forward your question to an expert on that model number who will review the matter further. I have provided a link below that may offer some good information for you to consider. Keep in mind that an expert will be in touch with you within the next two business days if not sooner. I wish you the best is this situation and have a nice day
by Manage My Life
November 23rd, 2012
Answered in 12 hours
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