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hvacmrfixit, HVAC Technician
Category: HVAC
Satisfied Customers: 192
Experience:  30 years of commercial and residential heating and cooling installations and troubleshooting
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I have a FRIDGIDAIRE FG6RC 080c-16b gas furnace. It wont

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I have a FRIDGIDAIRE FG6RC 080c-16b gas furnace.     It won't light (hot shoe won't even come on), but gives error codes alternating between "false flame / gas valve relay shorted", "pressure switch is open with inducer on", and "limit circuit open or external load on "W".    Main fan comes on and blows cold air.    Previously hot shoe would heat up, but furnace would stay lit for only a couple seconds before shutting down.   Where do I start?
Some thing is blocking either your outside venting (ice) or clogging your condensate drain(goes to floor drain) blow through drain hose and make sure its clear,also with gas valve shutting after a few seconds means the flame senser is dirty (small stainless steel rod oposite side of burner box then the ignitor,has a white or yellow wire attached to it) take that out and make shiny with a mild abrasive and reinstall
hvacmrfixit, HVAC Technician
Category: HVAC
Satisfied Customers: 192
Experience: 30 years of commercial and residential heating and cooling installations and troubleshooting
hvacmrfixit and 3 other HVAC Specialists are ready to help you
Customer: replied 8 years ago.

that didn't seem to be the problem, but here's some more info: after scientifically wiggleing the wires on the control board, removing and reinstalling the burner panel, the unit is functioning again. I expect it to go out again as it has in the past, though. The most consistant problem was the flame coming on for only 2 seconds and then going out, like the flame rectifier wasn't reading a flame and told the gas valve to shut. I cleaned the sensor in front of the burner which seemed to help. Would a bad control board cause all these different intermittant error codes or are they all symptoms of the same problem? I have very limited experience with this type of thing...if furnaces were made of wood I would have no problem.


Could be bad flame senser,they do go bad,not very common though.The flame senser operates on very low current could be loose or dirty connection at control board also
Thanks for using J A
Customer: replied 8 years ago.

after a month and a half of functioning the furnace has quit again, the symptoms being a little more consistant: The unit comes on, the red light stay continually on, XXXXX XXXXXght stays off, hot shoe doesn't come on, gas valve (I think) clicks on and off, exhaust fan runs.

I cleaned the flame sensor and blew out the condensate drain. The vent is not blocked.

Now what?

HI! Wait before spending that money on that board(not to say you may not have to but worth a try)After following your previous question and above the only thing it seems that hasnt been tested and is indicated by the blink code is the pressure switch. Check the hose and inspect for cracks or holes also see if a vacuum is felt on switch end while draft motor iis running if so then take the two wires off the switch and jumper together and see if that works if so pressure switch is bad. If no vacuum is felt make sure the opening on the hose barb from the draft motor housing has vacuum there if not turn off and clear opening with a stiff wire or long pin, also check draft motor housing for cracks. Let me know what you find out.

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