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My furnace is a Rheem Classic 90 plus. It works usually for…

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My furnace is a Rheem...
My furnace is a Rheem Classic 90 plus. It works usually for about 2 hours and then I get a green light that blinks once every 3-4 seconds.I tried replacing the batteries in my thermostat, dusting it, and checking to make sure it's level. It is. That did not fix it.I tried opening the furnace and cleaning the flame sensor with a steel wool brush. It is clean now, but that also didn't work.Need advice on what to do.
Submitted: 1 month ago.Category: HVAC
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Customer reply replied 1 month ago
Likewise I have flipped the circuit breaker to them and I have turned it off and on several times. None of which have worked
Answered in 1 hour by:
12/28/2017
HVAC Technician: airheatman, HVAC Technician replied 1 month ago
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,920
Experience: Furnace, A/C and heat pump specialist.
Verified

Can you look inside the burner compartment on label on side panel and get me the model on your furnace? Then look in blower compartment at board and tell me how many flashes between pausing . This will guide us in determining what is failing with the furnace.)Not if no peep hole and you have to remove blower panel to see control board, it will be necessary to hold door switch in to have power to board

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Customer reply replied 1 month ago
I can get the model number for you in a bit - away from the area for the moment. I do know that it is the Rheem Classic 90 Plus Economy version.The three lights in the blower board are all lit. The yellow flame light is solid when the flame runs. The power green light is solid. The green light for errors gives one flash every 3-4 seconds.
Customer reply replied 1 month ago
My furnace will be on for about 1-2 hours and then will switch off before even reaching the temperature set on the thermometer. I initially assumed something wrong with my thermometer, as I had it set to 70 but the temperature wasn't going beyond around 55.To check the thermometer I replaced the batteries, did a factory reset on it, ran the test modes and made sure everything was in proper order, and cleaned the wires inside of it of dust with a clean brush. This hasn't done anything to help.Later, I tried evaluating my furnace and cut the power supply at the furnace.When I turn it off and back on, the furnace fires up in normal sequence with no error codes whatsoever. Then, about an hour or so later it was not pumping hot air any longer (considering it was -5 degrees this was considerably upsetting). I then went to the circuit breaker, cut the circuits for the furnace and for the basement, however that also proved to have the same results.I looked on the internet here and evaluated the flashing light diagnostic codes. My furnace has a single green light flashing once every 3-4 seconds, which is the igniter failure code. Here, my furnace cuts off during use but doesn't have problems igniting though. When I looked up solutions, I was told to clean the flame sensor with steel wool (not sandpaper) so i did that (despite the fact that the orange light wasn't really flickering, growing faint, or blinking). This seemed to make the situation mildly better, as the home stayed above 60 degrees over night, but then in the morning I also noticed that the same code happened right before I left for work.
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

OK to verify the error code the model is important as Rheem uses several different board each a bit different.

When you return get me model number form label in burner compartment.

Also look on wiring diagram label and see if there is a legend telling us exactly what the 1 blink means.

Then together we will diagnose.

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Customer reply replied 1 month ago
I evaluated that from the inside of the blower panel when I was there. I will be able to get the number for you later today, but the error code was indicated as an "igniter failure" code - which seems odd to me as the ignition sequence has no trouble starting or sustaining for 1-2 hours
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

OK if the burners are already on and burning but it shuts off without giving any other code besides igniter failure (which as you state, is not in play at that time), you have a failing board and will need to replace.

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Customer reply replied 1 month ago
Which board do I replace?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

The board that is giving the false error code

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Customer reply replied 1 month ago
Let me get some pictures later this evening and we can assess from that also.
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Sounds great

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Customer reply replied 1 month ago
Is there locations on the board I can use my multi-meter to verify that it is failing?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Not really for the situation we have. If the furnace were failing at the time it should be igniting and giving this code we would test continuity on the igniter, continuity on wires from board to igniter and verify 120v to the igniter but it is giving us a failed iigniter code when it is not time for the igniter to be energized.

Now if furnace has completed it's cycle and ready to call for ignition again due to thermostat being satisfied but after temp dropping calling for heat again we might get the code .those are the things to test, but I am understanding every time heat is initially called for, the igniter does its job

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Customer reply replied 1 month ago
I have yet to see the furnace fail to light from a reboot or even changing the heat settings at the thermostat.
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Yes that is what I understood so we know the code is a false code from board.It is telling us igniter is not lighting when it is not time for igniter to be lighting

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Customer reply replied 1 month ago
Here are some pictures
6CBCCFED-6D3A-4A35-97C5...jpeg6CBCCF...jpeg5E513C0A-997A-48E1-B001...jpeg5E513C...jpegB1C49B4B-8807-45F0-A831...jpegB1C49B...jpegC0D21572-E31B-4301-B3D6...jpegC0D215...jpeg
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

OK now when furnace fails lets look at the board again.Make sure about the status code.I have the Rheem manual on my desk and the one flash code (indicated by the green OK light) says soft lockout, nothing about the igniter.

Are you sure the green OK light is fiving one flash pause?

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Customer reply replied 1 month ago
I’m not having. This problem happen at all now? I took off the cover to the burner and let that run without and no issues?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

If cover is still off, put it back on and see if it acts up again.If it does there is an issue with the pressure switch opening

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Customer reply replied 1 month ago
Still no issues?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Excellent mews.Thanks for letting me work with you.If my answer has been polite, professional,and thorough, please click one of the ratings before you go. If you still need help let me know!.Expert is not paid for assisting you until you rate answer.Feel free to follow up for 30 days at no additional cost. Bonus always appreciated if you feel justified.
To rate answer, please select one of the stars on the page.

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Customer reply replied 1 month ago
Well now it’s doing the same thing again? Pressure switch problems?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

I am suspecting board .Failing boards are known for erratic behaviour like this.

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Customer reply replied 1 month ago
I can usually smell some of the gas down there though
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

I don't think board is sending 24v to open valve.Can you check for 24v at valve when igniter glows?

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Customer reply replied 1 month ago
As of right now the electricity is out for my whole side of the street, but I am having he issue and it gets worse if I put the blower panel back on
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Wow that sure sounds like an air flow issue but we should be getting an error code for a limit not ignition. You might want to get an onsite tech on this since it is acting this way before replacing board

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Customer reply replied 1 month ago
I am at home now sitting in front of the furnace watching it work and waiting to see what happens when if it cuts off
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Let me know

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Customer reply replied 1 month ago
Flame went out suddenly and now it won’t relight?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Did we get an error code on board?

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Customer reply replied 1 month ago
It’s trying to light again still. Gas still pumping but no flame light on
Customer reply replied 1 month ago
No error code yet
Customer reply replied 1 month ago
Flicked it off and then on again and it started again
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Lights still 2 green on solid ?Amder amber out?

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Customer reply replied 1 month ago
It went out and the ***** *****ght went out with it. Like someone turned off the flame. After that it tried to relight and it wouldn’t. I powered it off and then back on and it restarted and lit all the lights
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Did you tell me you have already cleaned flame sensor and do you have a multi meter that reads millivolts?

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HVAC Technician: airheatman, HVAC Technician replied 1 month ago

It sounds like the board is momentarily losing the flame sense

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Customer reply replied 1 month ago
I did but I can try again on the sensor - I do have a multimeter
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Lets do this. I am going to send a link to a video. Put your meter in series with flame sensor between flame sensor and board. Then watch meter and see if the millivolts are dropping when it loses flame.

https://www.youtube.com/watch?v=a5u044OJBc4

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Customer reply replied 1 month ago
Once I test it the flame goes out?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Is meter in series with sensor and board?

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Customer reply replied 1 month ago
Not sure what you mean? I matched the settings from the video on the meter and placed the red on the sensor and the black on grounding.When I touch the sensor it measures close to 2.5 and then drops and the flame cuts out
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Watch video again.

One lead of meter should be on the flame sensor terminal and other on wire to board

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Customer reply replied 1 month ago
Alright give me a minute
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Take your time

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Customer reply replied 1 month ago
Alright we have flame and we are reading a bounce around 3-3.5
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Excellent.As long as we stay there burners should stay on .Watch the meter and see if it drops just before they go out

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Customer reply replied 1 month ago
Okay. Should o give this a given amount of time to test?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

How long did it take to fail last time?

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Customer reply replied 1 month ago
I flicked it on at home and it took maybe 15-20 min.
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Hopefully it will fail while watching I know that is a long time when waiting but we need to figure out what is causing loss of flame somehow

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Customer reply replied 1 month ago
Fair enough. I’m patient lol. I’m just also wondering if the wire connection to the sensor was loose or something and this establishes a better circuit I could be staring at this all night potentially ��
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Well if that happens, we will at least know all you have to do is clean the terminal and tighten the connection right?

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Customer reply replied 1 month ago
Thank you. I’ll keep you updated
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Sounds good

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Customer reply replied 1 month ago
No - sensor was reading 3.0 and it shut off
Customer reply replied 1 month ago
It’s not even starting the ignition process and there are no flashing green lights - they are both solid
Customer reply replied 1 month ago
Gas is starting in again now - new ignition sequence but no flame first try, second attempt at ignition also failed, blower is still running but no third ignition sequence is firing yet
Customer reply replied 1 month ago
Still two green solid lights but no ignition or flame
Customer reply replied 1 month ago
Gas turned off and then back on by itself as if to start a new sequence. Ignition worked first time in this case
Customer reply replied 1 month ago
play by play:1) flame shuts off while the meter read 3.0 at the flame sensor2) ***** *****ght turned off but the two green lights remained solid3) furnace kept gas going and failed two ignition attempts4) has and blower kept going momentarily and then turned off for a second5) has started back up in a new attempt for ignition6) ignition was successful on the new try after restarting
Customer reply replied 1 month ago
Help?
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Had to run get a shower. After 11 here. Give me a minute to read your reply

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Customer reply replied 1 month ago
No problem - after 11 here too but icy outside so it’s kind of important
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

OK now we have eliminated everything except for board ,gas valve and gas pressure.

Next is to determine if it is board.

To do this we will hook flame sensor back up.

Then find some alligator clips or a way to attach the leads of meter directly to gas valve terminals and again play the watching game.

See if we lose the 24 to 26 volts at the valve and that causes valve to shut off or if the valve shuts off while the 24 to 26 volts is still there.

If we are losing the voltage first the board is the problem.If not either the valve or gas pressure is the problem.

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Customer reply replied 1 month ago
Idk where the gas valve terminals are
Customer reply replied 1 month ago
Not sure what it’s supposed to look like
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Attach a picture of gas valve showing wiring

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Customer reply replied 1 month ago
Will have to revisit tomorrow night
HVAC Technician: airheatman, HVAC Technician replied 1 month ago

Will go from here

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Customer reply replied 1 month ago
Alright, it was measuring about 150 when off and now I started it and it’s measuring all over. Bounces anywhere from -35 to 35
Customer reply replied 1 month ago
Jumps to -168 when it shuts off
Customer reply replied 1 month ago
I’m on ACV and it holds 24.2 pretty regularly while running
Customer reply replied 1 month ago
Okay, so the gas shut off and then the colts plummeted?
Customer reply replied 1 month ago
volts plummeted
Customer reply replied 1 month ago
Still struggling with this issue
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