Goodman GKS90904CX Single Flash Error - Not the Flame Sensor
I have been trying to fix my Goodman for a few weeks now. It is a model GKS90904CX propane. I know one flash means a lockout. When I turn the thermostat on and off it will reset the furnace and allow it to run until it reaches temperature. This is an intermittent issue, could work for 2 days, and then happen again.
I have cleaned and then replaced the flame sensor. The ignitor lights up perfect, and I had a spare that I put in just in case and that did not fix it. I read that the circuit board could be a common cause so I replaced that wasn't expensive, but I am still have a problem. I also upgraded the thermostats, but the problem happened with the old and new thermostats.
When the furnace clicks on, the blower turns on, the ignitor lights, the gas ignites, and then after a few seconds it stops. I tested the pressure switch and it makes the clicking sound, and there is no water in the line. What else could it be? I live in the Northeast and would be looking at $300 for someone to show up, so any help that you could give I would appreciate it! I have a multimeter, but I am not too familiar how to use it.
Thanks!
Hi. I cleaned the original, and then replaced it. Neither corrected the issue.Hi. I cleaned the original, and then replaced it. Neither corrected the issue.
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could be an issue with the flame sensor. it sends a signal to main board once all burners have ignited. either, the flame sensor needs to be cleaned with steel wool, or the board isn't receiving the proper 3-5 milliamps. should be a flashing led light that tells you what error is present
a 'roll-out' safety switch it a small button looking device with a smaller tab/button sticking out of it, near the gas injection manifold. has 2 wires attached. the reset button is generally between these wires. it's designed to shut the unit off, by breaking the power circuit, if flame ignition causes fire to back flash out of the fire box. Press the little button and try relighting. if the roll-out pops again, and there was no roll out of flame, you made need to replace it.
Since the burners light this eliminates the pressure switch as the problem. Typically when the burners come on and shut off quickly a flame sensor, ground problem or the limit switch tripping are the main reasons. Since the flame sensor has been replaced, check the limit switch
You probably have had it fixed by now. But, in case not; The ground to the unit must be checked and verified. To check it properly, with multimeter on AC volts and the door switch in, check between the white neutral on the 120v side of the transformer to the secondary common (usually blue, could be grey). This voltage should read below 1 volt. If 2 volts or higher, you have a week ground and that must be found. If good, check between black 120v side of transformer to 24v secondary (red or orange), that reading should be 89-96 vac. This checks for proper polarity across the transformer. If this reading is 145 or so, reverse the black and white on the primary side, recheck for 89-96vac. If both of these are good, remove the wire from the flame sensor, check between this wire and chassis ground with call for heat, you should have 40vac or higher coming out of the board. If not, go to board where FS wire connects and check there. If voltage is lower than 40, it does not have enough for Flame sensor circuit. If it does, check between the Fame sensor and the wire to the sensor with meter set on DC microamps and when flame is present, should read 1-4 microamps. If not, the flame sensor is bad.
I forget what that code is...theres a sticker in the blower compartment or in your manual will tell you what 5 blinks means....typically its a flame signal error code....The flame sensor should be cleaned annually anyway to eliminate this problem...4 inches long and resembles a straight coathanger....clean/shine it up with emery cloth
Heat sensor....Or a flame sensor. Flame sensor is connected to a "single" wire under the buners usually found on the left side. Heat sensors (or flame rollout switches) are found surrounding the burner box. The most common bad one will be located just above the burners. it "should" have a small reset button in the middle just between the two wires. If the furnace does light even for a short time the rollout switch is not bad.
1
1 FLASH
Furnace fails to operate.
• Integrated control module
diagnostic LED is
flashing ONE (1) flash.
• Furnace lockout due
to an excessive
number of ignition
“retries” (3 total)1.
• Failure to establish flame.
Cause may be no gas to
burners, front cover
pressure switch stuck open,
bad igniter or igniter
alignment, improper orifices,
or coated/oxidized or
improperly connected flame
sensor.
• Loss of flame after establishment.
Cause may be
interrupted gas supply, lazy
burner flames (improper gas
pressure or restriction in flue
and/or combustion air
piping), front cover pressure
switch opening, or improper
induced draft blower
performance.
• Locate and correct gas
interruption.
• Check front cover
pressure switch
operation (hose, wiring,
contact operation).
Correct if necessary.
• Replace or realign
igniter.
• Check flame sense
signal. Sand sensor if
coated and/or oxidized.
• Check flue piping for
blockage, proper
length, elbows, and
termination.
• Verify proper induced
draft blower performance.
Try replacing the filter. Low air flow will allow the furnace to overheat. Sounds like a simple answer. Wish I had tried it before buying a flame sensor and controller. Live and learn I guess.
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