How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7497
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

I have a Coleman Model #dgaa090btda I replaced combustion

This answer was rated:

I have a Coleman Model #dgaa090btda
I replaced combustion switch. Had a indicator light flashing two times. This says combustion air switch stuck closed.
All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.

Hello, welcome to Just Answer!

Click here for the manual on the unit.
Please confirm this is it.

See page 13, locate the 'manual reset limit switch' on the left side of the diagram. you can find it on the unit by following the wire from the gas valve... see diagram for which of the two wires.

Press the reset button. Tell me how that works, we can proceed from there.

Please hold rating my service to you until we get this fixed or come to a viable conclusion.

Thank you !
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7497
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Phil and other HVAC Specialists are ready to help you
Customer: replied 3 years ago.

I reset. Still two lights flashing after 45 seconds.

Hello again, if the error code says the air pressure switch is stuck closed, and you replaced the switch, and it still issues an error code that the switch is stuck closed, then the control card or wiring to the control card is defective... it is giving you a bogus read.

That statement is in the range of 90% correct...but not 100% correct. We can do a few tests. remove one of the wires from the pressure switch and see if you still get that error code read.

We can go from there.

Customer: replied 3 years ago.

Yes still same code I removed 1 and tested and then the other. Reconnecting previous.

Thanks. the error code should have changed when you disconnected the pressure switch wire if the control card was working right... if you got the same code with the wire disconnected, the control card is bad for sure.

If you only go the same error code after you replaced the wire on the new pressure switch, then the chances are 90%+ that the control card is bad.

There is one anomaly, the wiring diagram provided for the model series, and that I have attached, shows no control card and lists no diagnostic codes. We need to compare the wiring diagrams in that for your model number against the instruction manual you have on site that defines the error codes.

Still however, these tests below are still relevant.

Please compare what your manual shows compared to the manual that coleman provides on line here.

Next test. Use a multi meter set on ohms across the pressure switch with both wires removed before the inducer fan starts... it should read open contacts, same as with the test probes held in the air. And it should read closed contacts after the inducer fan starts.

If it reads that way, the pressure switch is good and the control card is issuing a bogus error code... thats a primary symptom of a bad control card.

We can go from there.

Customer: replied 3 years ago.

I was finally able to get multi meter and tested pressure switch. Checked out.

I also turned on furnace and blew switch open. The furnace fired up, but as soon as I put hose back Furnace shut off.

Is there any other test for circuit board being faulty.

I would hate to send for part and find it was not the problem.

they run about $125


Customer: replied 3 years ago.
Relist: Other.
dont want to wait for phil

I agree with Phil. Replace the board. I read all of his troubleshooting and he led you down the right path. Please remember that an expert is not always right but if they know more than you you should take the advice. Also remember to rate his help.

just a follow -up to see if replacing the board helped
Customer: replied 3 years ago.

Yes it did. I also cleaned combustion motor and furnace is working perfectly.

I just finished installing this afternoon Great timing.

Thank you for your help.

You are welcome and I will pass the word along to Phil. One more thing, would you please finish the process by rating my help.

I look forward to helping in the future if need be.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
< Previous | Next >
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

Meet The Experts:

  • Phil


    Mechanical Engineer

    Satisfied Customers:

    Retired HVAC/ Electrical & Boiler contractor. Industrial
< Last | Next >
  • Phil's Avatar


    Mechanical Engineer

    Satisfied Customers:

    Retired HVAC/ Electrical & Boiler contractor. Industrial
  • gotoman for ac's Avatar

    gotoman for ac

    HVAC Technician

    Satisfied Customers:

    51 years of experience install design and repair of all makes and models of AC
  • Rick Mather's Avatar

    Rick Mather

    HVAC Technician

    Satisfied Customers:

    35 years experience, HVAC
  • Matthew's Avatar


    HVAC Technician

    Satisfied Customers:

    14 years experience in the HVAC field of service, installation, Manual J & D calculations
  • Kenton Guidry's Avatar

    Kenton Guidry

    HVAC Technician

    Satisfied Customers:

    12 years install/service experience.
  • Rick Ridley's Avatar

    Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    Retired But have had 30 years on the tools, Ex CORGI
  • Tom's Avatar


    HVAC Technician

    Satisfied Customers:

    16+yrs HVAC/R service. Residential Commerical Industrial