I have a goodman model#gpd075, it will ignite, flames come on, then go out for a bit, furnace runs, then the flames ignite again! Why are the flames reigniting? Have cleaned and even changed that rod...
The two most likely possibilities would be either the high limit or the pressure switch.
1. The High Limit: Located on heat exchanger outside panel, usually right above the gas valve. It will have two wires going to it. If the high limit trips, it will cause the flames to go out but the blower will continue to run. This is to cool the heat exchanger compartment back down to a decent temp, also for safety reasons. You can check continuity between the two terminals to see if the limit has opened. If this is happening, you could have a faulty or weak limit, but it is usually caused by another problem. Make sure all filters are clean and there is no restrictions in the air flow. The less airflow across the heat exchanger, the more likely it will overheat. Other possibilities could be a dirty blower wheel or dirty/clogged evaporator coil restricting the airflow. Another thing to check is the gas pressure going to the burners, if it is higher than the recommended amount, it could "over-fire" the heat exchanger as well.
2. Pressure switch: Located close to the inducer draft motor. It will have a small tube running to it from the inducer motor assembly. These have been known to go bad, but like the high limit, it's usually something else causing the problem with the switch. When the small motor (inducer draft motor) comes on, it causes a negative pressure in the assembly, pulling the pressure switch in and making contact. This lets the furnace know that everything is venting properly. The most common problem causing the switch to be stuck open is the small tube being clogged with debris or condensation, blocking the air flow. Remove the tube from the pressure switch, blow thru tube, if there is a restriction, remove tube from inducer motor and unclog the nipple that the hose connects to. Usually a small wire or paper clip is good to use. Also make sure the pressure switch is operating by sucking and blowing through the tube as it is hooked to the pressure switch. You should hear the switch opening and closing. Again, being able to check for continuity is best.
These are two common problems for the issue you are having. I hope this helps in some way and gets everything back to normal. Have a good day and a good holiday as well!
Dec 01, 2013 |
Heating & Cooling