My gas will not stay on. I have done the system checks and the yellow led does not blink, and is completely off. Cleaning the sensor does not help, and the sensor looks OK. Is is likely that changing the sensor will restore current to/from the sensor? What could be the causes and solutions to the yellow led being off?

Do you have spark ignition or do you have a glow plug? If spark ignition the orange led will come on as soon as the flame hits the flame senser. If old style glow plug ignition, the orange led will come on shortly after ignition, as soon as the glow plug turns off.

You almost never have to replace a flame senser.(but it is still possible). I would first run a new wire from the flamesenser to the control board(splice it right before it goes into the quick connecter at the board). I have found that the flame senser wire on the rheems tend to be the problem when there is no orange led coming on. If this doesn't do the trick, then I would replace the flame senser. If this still doesn't work, you most likely have a bad board. Please let me know what you find.

do you have spark ignition or do you have a glow plug? If spark ignition the orange led will come on as soon as the flame hits the flame senser. If old style glow plug ignition, the orange led will come on shortly after ignition, as soon as the glow plug turns off.

You almost never have to replace a flame senser.(but it is still possible). I would first run a new wire from the flamesenser to the control board(splice it right before it goes into the quick connecter at the board). I have found that the flame senser wire on the rheems tend to be the problem when there is no orange led coming on. If this doesnt do the trick, then i would replace the flame senser. If this still doesnt work, you most likely have a bad board. Please let me know what you find.

The ignitor is the glow type. It fires the burners up for about 10 seconds, the burners go out, then the main blower comes on. The little blower works as it should.

Ok. You have either a bad flame senser, a bad flame senser wire(very likely) or a bad control board(also very likely). Make sure you have cleaned the flame senser very, very well, with a piece of sandcloth, sandpaper, steel wool, or any abrassive material. You have already done this, but never hurts to do it again just to double check. Im going to list possible fixes in order from cheapest to most expensive. First being cleaning flame senser. Second, get a piece of wire long enough to reach from the flame senser to the control board, wrap the wire around the male spade of the flame senser and bypass any connections between the senser and the board. Leave the covers off the furnace and just temporary a wire from flame senser to as close as you can get to the wire on the board. Make sure you leave enough wire so that you can wire nut the wires together.
Third, replace flame senser.
Fourth , replace control board.

These are the steps I take when the orange led will not come on(indicating no flame has been sensed.

If what I say doesn't make sense, please ask questions, and I will try to clarify my answer. I have worked on rheem furnaces, new and old for many years, and I will all but guarantee that one of the things I listed is your problem.

I cleaned the sensor again with coarse steel wool, and I have a jumper of #12 primary wire fitted to the sensor securly, but when I follow the wire through the panel, it joins up with an embical that includes about a dozen other wires, that plugs into the board as a unit. What do I connect the other end too if there is no spade?

This is were I usually cut the wire coming out of the board(wire coming out of embical) make sure to leave it a few inches long, so you can wire nut it back together if the new wire doenst cure the problem. Sounds like your on the right track. If this doesn't do it, I would still try replacing the flame senser before replacing the board. Odds are if the wire doenst cure it, you have a bad board. Please keep me posted.


Ps, you may want to use a little lighter wire, even thermostat wire works just fine.

When the burners fire are you certain that they are all igniting? On in-shot burners you will have what are called cross over igniters. If these get clogged, and they do, then the flame may not lite the other burners. Since the flame sensor is usually located on the opposite end of the HSI this can prevent the sensor from rectifying the flame.

I really hope I didn't have you do all of this work for nothing. Please let us know if there is indeed flame at the senser. If there isn't flame at the senser, you will have to clean the cross igniter bar. We can explain how to do this if indeed this is your problem. Good luck, and let us know what you find.

I checked the wire with a meter, and it is OK, I tried a new sensor and no help, I am not completely positive the sensor had flame on it, but I think so, I will check it again to be sure. If flame on the sensor is Ok, and I think it is, then the new board will be next, right?

WOOPS, I checked to see if the burner for the sensor was lighting, and it was, then, the unit came on as normal. I ran it through 2 cycles and it seems to be working OK. Howerver the yellow led is flashing at a rate of about 2 flashes a second. What is going on??

An hour later, back to the old problem no heat, the unit is blowing cold air. Intermetent failure of the burners to stay lit?

Another hour later, it comes on as normal.

Another hour later, it makes 4 attempts then goes into lockout. Board? :rolleyes:

Sorry I've been away for awhile. The yellow led should be on steady(no flashing, flashing normally indicates a dirty flame sense, the flashing is way for the board to tell you to clean or replace the flame senser). But you have ruled out the flame senser and wire, so yes, the next step is to replace the board.. Keep us posted

Ok, I am back. Puter crashed, main board, LOL.

I replaced the board, and only the board. System works perfectly. I bought the remote flame sensor kit, but it was not needed. The instructions that came with that kit, and the main board for replacing the sensor, were confusing, and assumptive. My unit had a 1993 Manfacturing date and has had no service except cleaning and such by me. The written instructions make no reference to "what" the remote sensor replaces. It hade the remote sensor. What did these units have before there was a "remote sensor"?

Thanks for all the help sainttammany

You may need change Air pressure swich.

I have similar problem. No AMBER light. However my furnce runs fine. The wire on my flame sensot appears to built into the sensor, and runs to the mother board through a round black can, that attaches to the mother board. This sensor was replaced 2 years ago, and I was told they only last a couple of years. Is itthe wire itself that goes bad? What is that black can? I have a background in electronics and car repair (ASE certified) .

Please start a your own thread, it will have a better chance of being looked at by more people that way.

Also, make and model of funrace will help.

I believe you are speaking of the sparker, not the flame senser. The sparker wire hooks to a black plastic can looking device on the motherboard (if this is a rheem). Not sure of the exact correct name of the can looking device(I guess I would call it the spark sending unit). Normally the sparker and wire itself do not go bad, definitely should last longer than two years, but one never knows for sure. Usually when the sparker fails to spark, you need to replace the whole board, as parts on the board are not changeable. Now, before I replaced the board, I would replace the spark ingiter with wire first(cheap and easy to replace). If that doesn't do it, then the board it is.

However, you said that your furnace ran fine, so what exactly is it you need help with?

Just wanted to say Thanks for your time and knowledge. I found a reply of yours concerning cleaning the flame sensor. I did, it worked. Not only was I able to say my Mom a service call fee, but I was able to do something for her. Thank you! I hope to be able to pass on the kindness.

Thanks HDave. Glad I could help.