I have a Goodman GMP125-5 furnace that just quit working a few days ago. The furnace is laying horizontal up in the attic crawl space. I can hear it trying to start but after a while it shuts back off. Thinking it was the igniter I took the doors off and tested it with a meter. I got 35 ohms on it and then tried to restart and got three blinks on the error code led. This indicates a bad pressure switch I believe. I have ordered a new one but in the mean time tried drawing or blowing air through the air hose and could only get a very little air to move with a lot of pressure. Is there something else I should be looking at to confirm if something else might be bad in addition to or instead of the switch?
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Re: Goodman GMP125-5 furnace burners won't fire
Try to bypass the connection of the pressure switch to confirm if the pressure switch is really bad, and reset the unit. Monitor your pressure to be sure that its normal and not the cause of tripping your pressure switch.
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If the burners ignite and then turn off it looks likemthe flame sensor is the problem. On the opposite side of the igniter in the burners will be a metal rod, this rod needs to be cleaned with a steel wool pad. Once it's clean turn Furnace back on.
check to see that your condensate line is not plugged. next check the p-trap where your line goes in. also check your flue abs flue pipe see as it comes out of roof is it open or does it have an elbow coming off of it i usually install with elbow preferably less water goes in the units resevoir hope that helps u
have you checked the pressure switch and also to assure that the flu is clear? can you light the burner with a match and when you do how long does it run for? have you checked the clearance to the burner have you also assured that where the ignitor is pluged into is cleaned ive also noticed on another site there is a board issue with this model have you checked the board ? also have a look at this site as well its where I usually talk with other techs about issues they have with the goodman as well as other units http://www.contractortalk.com/f6/goodman-80-furnace-brand-new-wont-start-7006/ please message me back with the answers to the questions that I have asked and I await your reply Thanks again Rick
It sounds like you got a tough one there.When you say the blower starts up and then the igniter comes on are you refering to induced draft motor or main blower. The proper sequence is for the thermostat to call for heat at which point the induced draft motor should come on and run for 30-45 seconds,then the igniter should heat up for a few seconds then gas valve should open and main burner should light. After limit switch reaches set point for fan on ,blower should come on till after heat has reached thermostat setting then burner should go out, and blower run until fan off setting is reached on limit switch. If your furnace is not following this sequence and then not always doing the same thing in the same order,I would recommend that you change out board again. I have had several problems similar to this with Goodman units and all but one time installing new board solved it. That time I did everything I knew to do and talked to factory service techs repeatedly and finally installed new furnace. As far as your question about insulation,. As long as it is fire proof I can't see where it would hurt anything. Sorry I'm not more help. Good luck and thanks.
it sounds like the low temp limit switch, the one that cools the furnace down with the burner off and the thermostat open, when it cools to a point the fan stops, the other switch in burner area turns burner off/on, hope this helps
It must detect a flame a few seconds after the main gas valve opens or it shuts it down. Since you are hearing the burners fire up the ignitor is working and all the other safety circuits are working to allow the furnace to fire up.
The thermocouple is a small silver tube that protrudes into the flame of the main burners, remove it and scrub with scotchbrite pad or anything mildly abrasive. You just want to remove carbon and corrosion build up, re-install and see if it fires up.
I have two Goodman furnaces and if you are to maintain them your self you should keep on hand a thermocouple and a new ceramic ignitor. They will inevitably fail on the coldest weekend of the year and the only place to get them will be from a service company with a emergency service call ...$180.00 VS $60.00 off ebay or internet sales.
Also if your power vent fan is making ANY noise it is on its last legs and buying on in advance online will save you about $80.00 over the loca ldealers price......been there done that
dIf the burners are only staying on for about 5 seconds, you proably hav e a dirty flame sensor. Watch the burners light, the glow plug will light one end of the burners, in front of the last burner to light the will be a small thin rod, this rod must sense the flame or the gas will be shut down. Take a piece of steel wool and gently cleqan the rod.
If the igniter lights the burners the ignitor..... is not bad. Its like a light bulb.... it works or ot doesn't.
You are describing a dirty flame sensor. Dishonest contractors will sell you a new ignitor but clean the flame sensor when the are installing the ignitor. It is located at the opposite end of the burners than the ignitor. It has one wire going to it. Remove it and clean the rod with a piece of fine grit sandpaper. this should be done every year before heating season.