Question about Heating & Cooling
I have a Goodman gas furnace Model U-30. Electric Ignite. Went to turnit on for the first time this year. When setting temp on thethermostat, you can hear it click, but no fire. Followed instructionson door to turn off all electricity to it, turn gas off, wait 5minutes, turn gas back on, turn all electricity back on it. Still won'tlight. The only thing I hear is a humming noise from the unit itself. We didnot turn the gas off to it last year so I don't think it is off. Afraid to mess with that myself.
Observe the sequence of operation. stat calls for heat and sends a signal, to furnace. check for 24 volts to common and white wire at furnace.first the forced draft motor starts and should have 120 volts to the plug it attaches to. after forced draft motor starts the pressure or vacuum switch closes should show no 24 volt when checked across terminals. shortly after the ignitor glows and shortly after click the main gas valve opens and main burners fire. shortly after the indoor fan comes on and hot air blows into the ductwork. follow the chain of events to see what doesnt happen and it is a clue to whats broke. maybe start by switching fan switch on stat to on. if fan comes on you have high and low voltage thereby eliminating the stat power and transformer as a problem. if you can see the ignitor look for it to be cracked . look close dont touch any part of it .it is powered by 120 volts when energized from board. dont forget when you take the door off there is no power to the furnace so be prepared to tape the safety switch closed when you are diagnosing.
Posted on Oct 24, 2008
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Posted on Jan 02, 2017
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Dec 23, 2013 | Ovens
Nov 23, 2011 | Goodman Heating & Cooling
1. Thermostat calls for heat. 2. Draft inducer motor starts. 3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes. 4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas. Solution:You probably need to purchase and install a new ignitor. I would suggest that you inspect your ignitor closely for cracks. Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. The furnace's control board might not be supplying the voltage to the ignitor. If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.
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