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Goodman Model PGB 042100-1

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  • Goodman Model PGB 042100-1

    I am having a problem getting my gas furnace running. It is a package unit and the AC works. The blower motor runs when I turn it from auto to on on thermostat. When I switch thermostat to heat and call for heat nothing happens. I have 26 volts between the red and white wires from thermostat where they connect to the control board. All the limits are closed and the centrifugal end switch on inducer motor is open. It has a Honeywell Smart Valve gas control with a hot surface igniter. I have 26 volts going to the smart valve but only getting 13 volts out to the igniter/flame rod pilot assembly. My question is with the voltage being low out of the smart valve enough to prevent the sequence of operations from beginning with the inducer motor running? That voltage being low is about all I can find but just not sure if it will stop the sequence.

  • #2
    I don't mind trying DIY on the AC end of it but when it comes to the furnace you'd be better off getting a HVAC journyman to go through it so your good to go before winter sets in. Sure it could be something very simple but a good tech will point out any other deficiencies and take care of it maybe even while he's onsite.

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    • #3
      I'm not familiar with that model and so without a schematic it is a bit harder to tell what is going on.

      I'm guessing the heat is not working at all and the cycle is not initiating. What is the voltage between the white wire and black wire connected to the thermostat. It should be 24VAC. If there is no voltage then the thermostat or the wiring to the thermostat could be the issue.

      The 24VAC between the red and black wires are power from the control board to the thermostat so that only tells you that the 24VAC is present - it is not telling you if the thermostat is initiating heat.

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      • OleBones
        OleBones commented
        Editing a comment
        As stated in my original question, I have 26 volts where I am supposed to have it except out of the Honeywell Smart valve. I have 26 volts going into the smart valve but only 13 volts coming out going to the ignitor/flame rod assembly. And on the red and white wires from thermostat to board I have 26 volts. Red is power and white is heat.

    • #4
      Disconnect the ignitor and check for continuity (power off). Sounds like it failed (open). Common problem. How old is your system?

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      • #5
        Originally posted by pitboss000 View Post
        Disconnect the ignitor and check for continuity (power off). Sounds like it failed (open). Common problem. How old is your system?
        ignitor has continuity. best i can tell from the first 4 digits of serial number is it was built in April, 1995.

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        • #6
          Originally posted by Mightyservant View Post
          I don't mind trying DIY on the AC end of it but when it comes to the furnace you'd be better off getting a HVAC journyman to go through it so your good to go before winter sets in. Sure it could be something very simple but a good tech will point out any other deficiencies and take care of it maybe even while he's onsite.
          When you live on a fixed income you don't have the money to pay somebody and I have had some training and understand electricity and electronics. I have done repairs on it in the past but have never encountered this particular problem and just thought maybe someone could answer the question I asked. I am and always have been mechanically inclined and have done maintenance work on lots of different equipment.
          Last edited by OleBones; 11-07-2018, 12:52 PM.

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          • Mightyservant
            Mightyservant commented
            Editing a comment
            Then keep going brother, you'll figure it out. This is no different from trouble shooting anything else. Try all the obvious things many of which are openly discussed on many different sites.

            I learned a great deal trouble shooting my own unit HVAC but also offered a good experience and also helped me find a competent HVAC Journeyman when I reached the limits of my ability. Best wishes

        • #7
          Unfortunately I'm not familiar with the Honeywell smart valve to be able to offer specific advice. It looks like the igniter is part of the valve assembly. However I looked up an online datasheet for it - not sure if this is exactly your model but it may help. https://forwardthinking.honeywellhom...ll/69_1270.pdf. According to that you should have 24VAC at the igniter. Since you have only 13V it could be something faulty within the valve or a partial short on the igniter. Have you tried disconnecting the igniter assembly and rechecking the voltage?

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          • #8
            I'm also unfamiliar with this smart valve but there's a few things I'd check.

            Try cleaning the igniter rod tip of any carbon with a wire brush or scotch bright pad until its nice and clean to insure the proper voltage feedback.
            I'd also check the pressure switch used to detect blockages in the intake/flue. It can be temporarily jumpered out to see if its the problem. It's not uncommon to have rodents or even birds block the intake/flue with debris.

            Comment


            • OleBones
              OleBones commented
              Editing a comment
              This unit doesn't use a pressure switch. All it has is a high limit, rollout, and centrifugal switch in the inducer motor. All of those are in the state they are supposed to be. Probably end up replacing the smart valve since with low voltage out to ignitor it might sense a flame and if so nothing is gonna happen. Will try cleaning the flame rod and go from there. I have that same pamphlet on the smart valve and it does mention if it sees a flame, it won't llow anything to happen.

          • #9
            Originally posted by blue_can View Post
            I'm not familiar with that model and so without a schematic it is a bit harder to tell what is going on.

            I'm guessing the heat is not working at all and the cycle is not initiating. What is the voltage between the white wire and black wire connected to the thermostat. It should be 24VAC. If there is no voltage then the thermostat or the wiring to the thermostat could be the issue.

            The 24VAC between the red and black wires are power from the control board to the thermostat so that only tells you that the 24VAC is present - it is not telling you if the thermostat is initiating heat.
            I have a schematic that is on the inside panel. I'll try to attach a picture of it.

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            • #10
              OK so I had a quick look at the schematic and re-read your original post. So if I understand correctly you are saying that the voltage across the thermostat is present but nothing happens. The inducer motor should start running first. This will close the end switch and along with the other limits will power up the gas valve. Is the inducer motor running? If not you should check the inducer motor for continuity and also check that there is 120V to inducer motor. A failed gas valve will not stop the motor from running.

              Are you also seeing 24V on both sets of terminals on the gas valve. One is the power supply 1-3 and the other is the on control 2-4. You should see 24V from 3-1 and also 4 -1. If the inducer is not running you will see 0V from 3 -1. Page 14 of the document I attached has the troubleshooting procedure for checking voltage at the gas valve.
              Last edited by blue_can; 11-09-2018, 08:39 PM.

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              • #11
                "All the limits are closed and the centrifugal end switch on inducer motor is open."

                With the inducer running this switch needs to be CLOSED.

                If it's closed and you have power too the smart valve, but no heat, replace the valve. The ignitor on this is 24 volts.
                ~~

                ... it was plumbed by Ray Charles and his helper Stevie Wonder

                Comment


                • #12
                  Is the pilot gas coming on when the thermostat calls for heat?

                  Is the ignighter lighting the pilot?

                  If neither of those is happening you won't have heat.

                  Also, make sure you check your firebox as Goodmans have had a lot of problems with cracked fireboxes.

                  Mark
                  "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                  I never lost a cent on the jobs I didn't get!

                  Comment


                  • #13
                    Originally posted by ToUtahNow View Post
                    Is the pilot gas coming on when the thermostat calls for heat?

                    Is the ignighter lighting the pilot?

                    If neither of those is happening you won't have heat.

                    Also, make sure you check your firebox as Goodmans have had a lot of problems with cracked fireboxes.

                    Mark
                    A package unit isnt the same as the "regular" goodman furnaces. With a smart valve, if all the safeties and switches are closed, the gas will come on regardless if the igniter works or not.
                    ~~

                    ... it was plumbed by Ray Charles and his helper Stevie Wonder

                    Comment

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