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Pippi

Nothing but sound, not even any fury!

17 posts in this topic

We have a Sealed Combustion Downflow Gas Furnace. When we turn up the thermostat the furnace kickes on then there is a bit of background sound and then it clicks off with no heating going on or fan running. When we check the spot where there are blinking lights that indicate a code for diagnostics we have 3 flashes which is defined as Centrifugal Switch Stuck Open. What now??? I am a registerd Grasshopper can I do this repair? Have repaired washer and dryer several times with assistance from this site but not sure if this is beyond my novis capibilities!

Make: Coleman Evcon

Model: DGAT070BDD

Serial#: 960116289

Pippi

Edited by Pippi

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Need appliance parts? Call 877-803-7957 now!

Is it blue?

A make and model would be a good start

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What kind of "background sound" do you hear? Can you describe it?

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The sound is a hum like the furnace is trying to kick in, the same sound it has when it runs properly. But it makes this humming sound for less than a minute and then there is a click and it shuts off. At this same time you can check the indictor light and it is flashing 3 times which as I stated inticates that the "Centrifugal Switch is Stuck Open".

Make: Coleman

Model: DGAT070BDD

Serial#: 960116289

The furnace is biege in color.

Edited by Pippi

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... 3 flashes which is defined as Centrifugal Switch Stuck Open

where did you get that info ?

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The info is printed on a metal box that sits in our furnace interior, it is for trouble shooting any function issues. (Propane furnace)

Edited by Pippi

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Yes we had that repaired 2 years ago.

(Oops!) And you are right I was reading the list on the user manual and just thought they were the same.

"Combustion Air switch failed to close!"

Edited by Pippi

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"Combustion Air switch failed to close!"

that's better..

Does the Combustion Blower run ?

There should be small rubber tubing connecting to the Air (pressure) Switch

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I am not sure what the combustion blower is and the air pressure switch as well. (I will do some investigating) but if I switch the heat - off - air to off and back on then bump the temp up to 75 - or higher it will cycle through and then kick on. We have had the thermostat tested and replaced the battery etc and still the lack of it starting when it is cold. Occationally it will kick on so to us it is a mystery! Have a call in for the repair fellow but that has been 3 days now and so we are manually adjusting the heat switch when we wake up and it is really cold.

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If your tech is making you wait three days you need another tech.

The combustion blower, which Coleman calls a booster assembly and is known to rest of the world as a draft inducer, is a small fan mounted to the front of the furnace. You should hear it start as soon as the thermostat calls for heat. It will run for 30 seconds or more before anything else happens. During this time the furnace control checks the status of a pressure switch which is connected to the inducer housing by a 1/4" tube. If the switch is still open, the control assumes there is no draft being induced and shuts down the system. That's the quick and dirty rundown.

Your problem is:

A. bad inducer

B. bad pressure switch

C. bad thermostat

Since I'm not standing there, listening and smelling, unable to truly grok, I'm going for B. bad pressure switch.

Edited by jb8103

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intermittent inducer issues can also be:

d: crap built up in port for hose connection

or e: squirrel, bird nest, wasp nest, etc. in flue pipe. (lots of these at beginning of heating season)

interesting note: we found a wood duck jammed in a pvc flue pipe this year. he made it clear to the inducer, and his bill was hitting the fan cage.

Edited by Bullstok

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any pictures ?

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3 flashes which is defined as Centrifugal Switch Stuck Open

If this was the actual terminology that was used on the error code list then there is a high possibility there isn't a pressure switch on this unit. I'm not sure if it's Coleman, but I know I have ran across at least one of these that actually has a centrifugal switch in the end bell of the inducer motor and it takes the place of the pressure switch, (probably not something that was used a lot since that would not really let you know if there is a draft or not, just that the motor was running and there should be a draft if the flue isn't plugged).

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intermittent inducer issues can also be:

d: crap built up in port for hose connection

So true. Carrier has this condensate collection box that clogs solid with accretion, and that reports a pressure switch error.

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If this was the actual terminology that was used on the error code list then there is a high possibility there isn't a pressure switch on this unit.

The user manual says one thing and the furnace data plate says another. You're shocked, I know.

Truly, I can't find any pressure switch on the PartsDirect parts list.

Gotta be there. If it was a bad inducer you'd hear it or smell it.

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The user manual says one thing and the furnace data plate says another. You're shocked, I know.

Truly, I can't find any pressure switch on the PartsDirect parts list.

Gotta be there. If it was a bad inducer you'd hear it or smell it.

I've seen the inducer break at the hub, or come loose from the motor shaft, so the motor runs but doesn't induce a draft, and they won't even try to light then

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