Help My 86-yr. Old Mom Get Heat! (Coleman DGAH056BBSB)

[strum4u]

Hello all,

I'm a newbie to the board, and am hoping I can get some help resolving a Coleman Gas Furnace issue.

A week and a half ago, my mother's Coleman DGAH056BBSB Furnace would not come on, having not used it for months, since the last cold weather here in the Northeast.

When setting the thermostat with a target temperature above the room temp, one hears the customary clicking. Then, I can hear the transformer come on and another click inside the furnace, but the inducer motor never starts its draft mode to then activate the pressure switch and then ignition.

After 30 seconds to a minute, the control diagnostics then flashes the dreaded three (3) times, signaling "Combustion air pressure switch failed to close."

I purchased a new and improved Honeywell Combustion Air Switch, recommended by Coleman techs for this particular furnace, but the switch did nothing to fix the problem.

Next, I used a multimeter and confirmed 24 Volts to the Transformer.

Also, I ran 115V of power directly to the inducer, and it works fine, with the squirrel cage spinning smoothly and quietly.

I talked to one friend who works in home remodeling, and he suggested that I get a new circuit board, as likely a capacitor or relay was blown out. I purchased a new circuit board, and carefully installed it with attention to detail, making sure every single wire was connected exactly where it should be.

But, to my dismay, the inducer still doesn't come on at all. Hence, here are some questions as to what my next step should be:

1. How can I test the upper limit switch, and could this be the problem, as the only
other wires in circuit to the inducer, are the upper limit switch, and regular limit
switch, the latter of which is near the ignition?

(Please note the the reset button doesn't seem to move at all, and unless I stand
(corrected, shouldn't this button click down into place, similar to how a reset button
(would on an AC power strip, for example?)

2. Before purchasing and replacing both limit switches (if recommended) should I take
the gas cover off and clean the flame sensor with steel wool, and check for any
spider webs, etc., or is my problem with the inducer, and not gas or ignition, as they
are secondary to the inducer motor coming on first?

3. Am I correct that the digital Thermostat doesn't seem to be the culprit, as it does click
when the target temp. is set above room temp, and then the transformer comes on and
another click is heard from the furnace?

In closing, thanks for any and all suggestions. My mother is on a very lean, fixed income through S.S., and I'm currently under-employed as a musician, trying to fix this problem for her.

I've already invested a good amount of time, researched and purchased the correct parts, and honestly thought I would have fixed this by now. Mom is a heart patient with bad circulation, and she needs her heat. So far, we're getting by with electric heaters, but they will NOT be suffice in another week or so!

I'm perplexed by this problem, yet determined to find a solution, and kindly ask for your assistance to get this 86-yr. old her heat back.

Appreciatively,

Glen

[Mark]

If the booster motor did not turn on instantly, replace it. If it's not running, it can't trip the pressure switch which is causing the fault code on the control board. You can see and order the booster assembly for your furnace here: http://www.aberdeenhomerepair.com/store ... oster-assy

Mark

[strum4u]

Hello Mark,

Thanks for your reply!

I did remove the inducer from the furnace, placed it on the floor, and hooked up an electrical cord that I use for testing automotive parts, like cooling fans. blower motors, etc. On the power plug for the inducer there are only two wires. I directly connected each of the bare wires of the zip cord to each respective terminal on the power plug, and presto!

The inducer worked perfectly, like I stated in my post. It built up speed quickly, was powerful and smooth, and was as quiet as can be.

Wouldn't that rule out the inducer, as I ran power to it and it performed as it should?

Isn't there something impeding the electric power from getting to the inducer?

Unless there is an internal capacitor or something that I'm unaware of, why would I need to replace an inducer that passes a bench test?

Thanks for a clarification of your suggestion that I replace the inducer.

Regards,

Glen

This is why I

[strum4u]

Mark,

After reading your post more closely, I see that you are referring to the draft booster assembly, and not inducer blower motor, the latter of which I've tested.

Is there any way to test this booster assembly, or is has that already been done, by its failing to come on?

What is the little black box on the outside, with silicone tubing that attaches to the combustion air pressure switch, and is this component included with the part, the link of which you included in your last post?

Finally, it appears that a good deal of dismantling is required in order to replace the booster assembly, including removing the gas valve assembly, and the housing to which it is attached.

Am I correct with that assessment?

Thanks again for your help!

Regards,

Glen

[Mark]

Hi, You can test the booster assembly the same way. Run power directly to the 2 wires and see if it runs. Yes, you need to remove or loosen all that stuff below so the draft booster can slide down and out. The little black box is included.

Mark