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  • Troubleshooting and I don't know what to do next

    Help!

    I have an Outside Armstrong Furnace/AC Package. All I know about the model is that it is a GHC. This package was here when I bought the house in 1998.

    Here are some photos of the compartment where I am trying to troubleshoot.

    http://s172.photobucket.com/albums/w8/sorryexcuse/

    PROBLEM: Furnace is blowing cold air into the house when I need warm air.

    WHAT'S CHANGED: Something changed but nothing that was noticeable like noises or smells and it is not a start-up or shut-down situation. It just stopped giving warm air in the middle of the night three days ago.

    OBSERVATIONS: Opened up the cabinet and had my son turn the power on inside the house. Prepurge fan starts up and runs. About 2 minutes later, the blower comes on. Both continue running and running and running.

    No spark or sound from the electrode. Jets don't fire. Can't find a pilot to see if it lights but it's confusing that the electrode for ignition is at the other end of the run from the flame sensor.

    ACTIONS: Installed fresh filter. Checked all connections, removed and cleaned some suspect connections. Closed it up and went through start up procedure. Same thing - cold air blowing.


    Any ideas for testing here?

  • #2
    Re: Troubleshooting and I don't know what to do next

    Kathleen

    Please shut off power and gas valve near furnace for safety reasons. Then remove the service cover and look over all wiring and connections up above the burner. Because the blower runs, but it seems to not attempt to light the burner, I think an overheat sensor may be the issue. Connections to them must be good. This is only an idea. Get a good worklight and really look over everything. If it looks bad, try cleaning it and reconnecting. I have a feeling you'll more than likely need a good HVAC tech with the service manual, but it might be something simple and you'll see it. When you try it again (power up) do leave the gas valve off at first. Does the igniter either glow orange hot, or does it make sparks? If not, you won't light up the burner. In that case check wiring and connections but please don't change any of them. Also look for any little high temp hoses that go to a forced draft sensor. I didn't see such in your pictures, but there might be one. If it's busted, pulled off or has a little hole in it, then it needs to be replaced. Again, give it the eyes and if something looks bad it may well be. Do be careful and always think on the side of SAFETY MUST COME FIRST.

    Comment


    • #3
      Re: Troubleshooting and I don't know what to do next

      i think the problem most likely is the grey ignition moduel located top left. you unit is spark ignition not a hot surface ignitor(glow plug). it is more common for this part to wear out rather than the spark ignitor to go. your flame sencor looks like it is in very dirty condition much like the rest of your unit. there is a large amount of rust where your exchangers are and that warrent some investigation to why there is so much moisture getting in to your unit.
      how is it that so many answers are in the instructions

      Comment


      • #4
        Re: Troubleshooting and I don't know what to do next

        Thanks for the ideas guys.

        I will try the power on, gas off idea in the morning with my ear closer to the furnace. Thinking of removing the shield above the jets but not sure it's going to give me any better view of what's going on. The jets are installed directly over top of both the ignitor and the flame sensor so to remove either I would have to mess with the jets themselves. Not too sure that I want to do that.

        Is there a way to test the electrode/ignitor without removing it from the furnace?

        Will test the limit control and heat sensor in the morning too.

        Have a great night.

        Comment


        • #5
          Re: Troubleshooting and I don't know what to do next

          Well I tried the power on, gas off this morning. Still no electrode/ignitor sounds.

          So i cleaned the connections to the switches and coil.
          Did some Ohm testing on the pressure switch (good to go), temp limit switch (good to go) and coil (no reading).

          Reconnected everything and started the furnace.

          NEW OBSERVATIONS: After the prepurge came on the electrode/ignitor clicked, clicked, clicked away. But no flame. Due to the location of the ignitor, I could not see if there was any spark. But the sound leads me to believe that it is working. (Is this a right deduction?) Cycles 3 times and then locks out but the prepurge and blower keep blowing.

          Volt tested the two switches and they both gave readings of 25 volts each.

          Reset the furnace and the same observations occurred. Prepurge, click click click, Blower. No flames.

          Am I supposed to get a reading on the coil with an Ohm test? Just replaced a coil on my gas dryer based on a no-reading with the Ohm test and it is working like a charm.


          note to proplumb: I had foolishly supposed that the poor shape of the insides was due to the age of the furnace and the fact that it is an outside unit exposing it to the elements. It rained all night last night and well into this morning. When I opened the cabinet I found some drops of water were getting in there and travelling down the wires. Could not locate the source yet but will keep on it. Moisture is definitely getting in there and I appreciate you pointing this out to me. This could be the root cause of all of my trouble.

          note to Woussko: Think giving a good cleaning to the contact points allowed the ignitor to work this morning. I thought that I had done a good job cleaning the contacts yesterday and didn't want to go through it all again. But it was worth it. Appreciate that. There are no high temp hoses from the switch to the prepurge in my unit. Must be the design as the prepurge does not have anywhere to attach a hose to and I don't see a connection for a hose on the temp sensor either.
          Last edited by kathleen; 04-01-2007, 11:06 AM.

          Comment


          • #6
            Re: Troubleshooting and I don't know what to do next

            Kathleen

            Did you remember to turn the gas back on and try it? I get forgetful sometimes and wondered why my own furnace wouldn't light up only to find I had left the gas valve closed. Something else you might try with everything off is to remove and clean up the flame sensor. Depending in the type used they need to be clean. Normally if they fail it will fire up and then quickly shut off the electric solenoid (spelling) valve.

            Note: If you have trouble with frozen screws, please do not try turning them too hard. If they bust you'll really have some work to drill and try removing them with a little E-Z out. Try some Liquid Wrench (just a little) and let it soak in. Once any screws are out, it would be well to replace them with new ones. I recommend going with stainless steel if you can.

            Do you have a small torch by any chance? If you do, light it and hold it near the igniter but not to it heats up the igniter and then see if it fires up. Please no matches or you may really burn your fingers. If it does light up and stays on, then you know the problem is with ignition. If it lgihts but goes out quickly, I would go after the flame sensor.

            As for the Ohm meter readings, that's where you really need a service manual. Be careful as a spark coil can really zap you hard.

            I have a gut feeling you would do well to have a good furnace repair tech come by and check over everything. Give them the brand and model info and any other info you can when calling.

            Comment


            • #7
              Re: Troubleshooting and I don't know what to do next

              Ha Ha Ha! Of course I forgot to turn the gas back on Woussko! I was standing there listening to the click click click of the ignitor and watching for flame and wondering what the hey when I looked over and realized I left the gas off. I wasn't about to admit it though.

              Once I realized my mistake I shut the power off again to reset and turned the gas and power on together. So those are my observations with both gas and power on in the post above.

              Tons of frozen, decaying screws in the furnace. Will have to pick up some new ones and some Liquid Wrench (thanks for this advice). Haven't used it before.

              I don't have a torch but I do have some long handled matches. Will they work? They are about 10 inches long.

              Was thinking maybe this afternoon when I take another run at it, I will place a mirror in there where I'm having trouble seeing to see if there is a spark with the click click click.

              With that Ohm reading on the coil, (didn't touch the spark coil - too afraid to go there!) - just the coil that sits up top of the gas valve. I am thinking that the coil is not letting the valve release any gas. So the matches would prove that out too.

              It's impossible to remove the flame sensor without pulling all kinds of things apart - the screw heads are on the other side away from me. So if I do finally get the jets to start and then go out, I will tackle it at that time. I have reached back in there with some fine sandpaper and cleaned it up as best I could under the circumstances (difficult access).

              Comment


              • #8
                Re: Troubleshooting and I don't know what to do next

                When it is clicking do you have 24V across the gas solenoid? If it is zero volts then the problem may not be the valve but the control board that drives the valve. Is there an led on the control board that may be flashing a trouble code?

                Comment


                • #9
                  Re: Troubleshooting and I don't know what to do next

                  I didn't think to volt test the coil (well actually I did but was afraid not knowing what level to have my tester set to). I only did the Ohm test on the coil. Now that I know I will check it when I am out there this afternoon. Does the test have to be done exactly while the ignitor is clicking or is it okay to test at any time while the furnace is running?

                  I wish I had one of those handy boards! No, mine is a non-integrated circuit control board so no clues there.

                  Comment


                  • #10
                    Re: Troubleshooting and I don't know what to do next

                    I think it has to be as it is clicking as that is the only time the valve will be picked. Once the clicking stops if the flame sensor is still cold then the valve will be closed for sure. There has to be some kind of relay system in your furnace to control the motors and sensors, maybe your relay got wet and is corroded

                    Comment


                    • #11
                      Re: Troubleshooting and I don't know what to do next

                      That makes sense. I will time the test to the clicking.

                      If a relay means limit switch, I do have two of those. Can't spot any more. And don't see any wires leading off into unknown areas to trace to another switch. Have Ohm tested both. Volt tested both. So they are both working as they are supposed to. Just not sure if one of them is saying "no light fire" to my control board.

                      Comment


                      • #12
                        Re: Troubleshooting and I don't know what to do next

                        Most furnace controls run at about 24 Volts AC so you would set your meter to read that when you connect it across the coil of the gas valve. Normally they will start ignition (spark spark spark) and open the gas valve at the same time. With a hot rod or tube (orange hot) that is powered up for several seconds and then the gas valve opens. In either case if the flame sensor gives a zero to the contoller then the gas valve power is cut off pretty quick.

                        Long matches: They should work OK. Just be careful of a POOF flash when the burner lights up. If you a pair of goggles and/or heavy duty leather (not cloth) gloves, I would suggest wearing them. Have another adult nearby so that in case something does go wrong he/she can close the gas valve and shut off power fast. You need to do both and quickly.

                        A mirror may come in handy, but remember that if it's bright daylight you won't normally see the sparks very well. You may need a way to shield the sun or other light for the testing.

                        Limit Switch: This is normally a thermal switch that normally is closed and opens only when a set temp is met. That would give a very low resistance reading at room temp and totally open if overheated. There are several styles of them and it normally has 2 wires connected to it. This will be up above the burner and other than for the connection will be inside the furnace. It may be about 6-12 inches above the burner tubes or in some cases up high being it is a hot air furnace.

                        The flame sensor can be of several types and to read that with your meter would require knowing what type you have.

                        The ignition coil is normally a transformer. The primary would be 120 Volts AC in most cases. The secondary will be on the order of 10,000 - 25,000 Volts but only a few 1/1000 Amps. To check the output, you would need a test spark plug with a gap of about 0.06 inches or so. Don't try anything with your meter or most likely it will be bye bye meter. You could check the input Voltage with it set for 200 -300 VAC.

                        I still want to know what happens if you try to light up using a little fire such as a long match. The draft may put the match out on you. A small torch would be better or maybe you can get inventive. Do you have or know anyone with a gas grill? The lighters for such should work just like the ones used for camping stoves and lanterns. See picture
                        Last edited by Woussko; 04-01-2007, 03:54 PM.

                        Comment


                        • #13
                          Re: Troubleshooting and I don't know what to do next

                          Kathleen

                          You must be the kind of lady us guys dream about. You ain't scared of dirty hands, getting burned (not too bad, I hope) and doing some "grunt" work now and then. Down here in "Insanityville" almost all females are too YUP-PEE (my way to spell it) type. They would hire someone to do this work for them or they would just scream at the furnace and think they might make it work out of fear.

                          I bet you do what you can to take care of your car / truck and your home. We need more of you around. VASandy is another example of a lady that likes to actually do things around her place. Maybe you'll get say hi soon? She is normally in the woodworking area.

                          Comment


                          • #14
                            Re: Troubleshooting and I don't know what to do next

                            suggestion one
                            if there is water traveling down the wires, maybe your spark ignitor is wet, if you have had this problem with your bbq at home you will understand that it will not work if this is the case.

                            if you are getting a spark it sounds as if the ignition moduel is working okay. a nail file to your flame sensor would be a good next step. check to see that your gas valve is gatting 24 volts to it, this should happen just before you here that clicking sould coming from the ignitior.
                            how is it that so many answers are in the instructions

                            Comment


                            • #15
                              Re: Troubleshooting and I don't know what to do next

                              Waited all afternoon for my son to get home so he could be my standby to shut down the furnace if anything happened. He's still not here, the sun's going down and it's starting to rain again. Will try to do those tests tomorrow after work and report back.

                              Thanks again everyone for your great ideas. I'd be lost without you.

                              Have a nice night.

                              Comment

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