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Old 09-27-2009, 02:00 PM   #1
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Troubleshooting Robertshaw Ignition

Right before this past Spring, me and the wife went through a trying time with the heat. It's a Coleman Evcon- model# DGAT056BDC/ 56BTU Input 46BTU Output

What's been happening is the heat will try to cycle on and not follow all the way through. What I mean by that is: the glow rod will light up and the gas will kick in, then there will be a good blue flame for about 10 seconds then the flame shuts off along with the glow rod. The smaller blower motor on the right side will keep running and will not shut off until the thermostat is turned down. Unless it is turned down, the unit will keep trying to turn on for about 3 times then the glow rod and gas quits turning on except for the smaller blower motor. In order for us to get the heat running, we let the unit try to cycle on and when it fails to we try the same thing for about 5 times until it finally stays on.After doing the last, most of the time the heat would stay on all night until we turned down the thermostat.
We did call out a tech. for this issue and all he did was use some sand paper to take off some of the carbon on the glow rod. He put that back in and that lasted for about 2 weeks. It then started to do the same thing again.

Ignition Control--> Robertshaw Model# HS780 43NR-306A
Part# 100-00812-45 Input Voltage 120/24VAC 60Hz
Evcon 1474-006


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Old 09-27-2009, 02:43 PM   #2
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How old is the furnace? Remove the front cover and take 3-4 pics of the burner area and ventor fan (pushes smoke to the chimney) and post them here or photobucket/links here. Lots of different Coleman units and some I know some weird problems with.


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Old 09-27-2009, 09:51 PM   #3
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could be flame sensor, dirty or bad ground,
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Old 09-27-2009, 10:28 PM   #4
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Sounds like flame sensor needs cleaned.
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Old 09-28-2009, 10:49 AM   #5
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The furnace proves the flame through the ground. If the rod and burner surfaces are not clear it will not prove the flame. Also the furnace needs a good earth ground and the control needs to be well grounded. Could also be a faulty control. I would suggest checking the roof jack, (chimney), to make sure the center flue pipe is not rotting and falling into the furnace and plugging the flue passage. This will cause the furnace flames to go out due to a lack of oxygen.
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