Luxaire furnace only blows cold air - no heat

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  #1  
Old 05-03-16, 03:17 PM
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Luxaire furnace only blows cold air - no heat

forced air furnace Luxaire model PBKM-LD12N060E

furnace calls for heat, inducer comes on, blows fine. ignitor starts to glow, hear gas valve click, no flame. ignitor goes out and tries 3 times and get 7 flashes which basically states lockout due to retires.

What should I look for to fix this?
 
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Old 05-03-16, 03:31 PM
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Sounds like it's not getting gas. Could be a plugged orifice or a bad gas valve. Check the orifice and try a few light raps on the gas valve when it is supposed to be energized.
 
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Old 05-03-16, 03:44 PM
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that's what I was thinking was the gas valve I did tap it a couple times and still nothing
Where would I check foe the orfice I'm not sure where that's located on the valve
 
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Old 05-03-16, 04:25 PM
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Check the advice at repair clinic dot com. They suggest three possibilities: (the following is from them)

check the ignitor: The igniter gets very hot and glows bright orange to light the gas burner. If the igniter fails or cracks, the furnace won’t heat. To determine if the igniter is faulty, remove the igniter and inspect it for cracks. If the igniter is cracked, replace it. If the igniter is not cracked, use a multimeter to test the igniter for continuity. If the igniter does not have continuity, replace it.

Or the flame sensor: The flame sensor monitors the burner to detect whether or not a flame is present. If the flame sensor is defective, it might fail to detect a flame. If the flame sensor does not detect a flame, the control board will shut off voltage to the gas valve to prevent the furnace from heating. Sometimes, if the flame sensor is dirty, it will fail to detect a flame. Try cleaning the flame sensor with a fine abrasive pad. If the furnace still doesn’t heat, replace the flame sensor.

Or draft inducer motor: The draft inducer motor draws air into the burner and then exhausts it out the flue. When air flows through the burner, a pressure switch closes to signal the control board that the furnace has proper air flow. If the draft inducer motor is defective, it may be unable to close the pressure switch, causing the ignition process to stall to prevent the furnace from heating. If the draft inducer motor is at fault, replace it.
 
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Old 05-03-16, 04:54 PM
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The orifice will be at the end of the gas line from the valve to the burner. They usually will unscrew from the end of the gas line.

If you have a multimeter you can verify that the control is trying to turn the valve on. You should measure about 24VAC going to the valve at the time gas is supposed to be on (about 30 seconds after the inducer starts).
 
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Old 05-03-16, 06:33 PM
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thx, Ill do some more checking tomorrow I did have approx 26 volts to the valve when it was calling for gas.

acts like not getting gas.
 
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Old 05-03-16, 06:56 PM
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X.... the suggestions from repair clinic are very broad sometimes misleading.

It's definitely not the inducer or you wouldn't get the igniter.
It's not the flame sensor because there is no flame to sense.
If the igniter isn't glowing white hot.... that MAY be the problem but not likely.

If you DO have 24vac on the gas valve then it would appear the gas valve has a problem.
As mentioned.... make sure the gas valves are on. Some gas valves have an on-off switch on them.... try sliding that from off to on several times as it can get corroded.

The 24vac to the gas valve will only be present for about ten seconds.... starting about five seconds before the igniter shuts off.

See if this is your manual. It has your model number listed but no 7 flashes in the code section.
Installation Manuals-PartsLists/80AFUE Furnaces-PBKM-PBKD-PBKM-PBKD-Install.pdf
 
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Old 05-03-16, 07:11 PM
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thx. I will check more on it tomorrow .
Im going to check the orifice to see if plugged
I did a couple turns of the on off before and didnt change anything,
There is an additional code error on the door all the 7 flash is it a 3 cycle time out.
 
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Old 05-03-16, 07:26 PM
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OK... then the manual link I post for your unit should be correct.
There is a full diagnostic routine in it.
 
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Old 05-08-16, 11:01 AM
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changed gas valve furnace is working again. I bought a used one because the new one looked way different and wanted to be sure to get correct one.

thx for help.
 
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Old 05-08-16, 11:09 AM
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New gas valves usually do like different as they are the latest revision of the product.
You may find just one valve now will replace many older valves.

As long as the used one is working correctly you should be good.
 
 

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