Furnace Flame Sensor Testing and Flame Rectification Troubleshooting!

[@acservicetechchannel]

Tool List- www.amazon.com/shop/acservicetech Support- www.patreon.com/acservicetech For those that are looking for the tools used in the videos: (Linked Below) Here is the Link for the newer UEI DL479 Multimeter with temp sensor- amzn.to/2jtsUbJ Here is the Link for the newer UEI DL469 Multimeter- amzn.to/2jw4ePJ Here is the Link for the UEI DL389 Multimeter used in the video - amzn.to/2naJr9o Here is the link to the Fieldpiece SDMN6 Dual Pressure Testing Manometer with Pump-amzn.to/2jyK5Ka Here is a link for the Supco Magnet Jumpers amzn.to/2gS4h6z Here is the link for the Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Other tool links can be found in the video description section. ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.

[@jamesspies630]

dude I'm learning so much. I watch at least once video a day. its making me a better tech. keep the videos coming.

[@acservicetechchannel]

That is awesome to hear James!

[@dporrasxtremeLS3]

Yes! Craig! Thanks!

[@brettmorgan5612]

I have to say that I truly look forward to getting home and watching several videos every night after a long day in the HVAC field! Your videos have helped me become a better tech and I enjoy learning something new every day. Thank you for all that you do in each and every video.

[@acservicetechchannel]

I really really appreciate you taking the time to write that note Brett!

[@originalCN4]

My parents aren’t really flowing with cash, so I end up doing maintenance on things there, this was an issue( still is really), so this is gold..... God bless you man

[@ChrisJames-tf8yw]

This video saved me. My problem was a bad ground to the circuit board. I could still measure microamps at the flame sensor. But the board would lock out. I thought I would need a new control board. After seeing this video I decided to try to find the ground wire. The ground wire screw was part of the chassis and had vibrated loose and corroded. I drilled a hole and remounted the ground screw. The furnace acts like new.

[@dporrasxtremeLS3]

Thanks for sharing this example!

[@Jeepjones85]

I’ve been in the field about 18 years and I by happenstance came around a lose ground wire at the burners and this unit just would not run everything was checking out. I tell you I never forgot that lesson it’s only ever happened twice the other time the ground was cut when the service tech before me changed out the draft inducer. Great video

[@acservicetechchannel]

Thanks JonesHVAC!

[@jasonvoorhees8545]

Good video, concise and easy to follow. I like the way you explain things.

[@acservicetechchannel]

Glad it was helpful!

[@phillipjoy8191]

Thanks for your reply.Best teacher on the internet.

[@acservicetechchannel]

Glad you enjoy the videos and responses Phillip!

[@riggamawesome1]

Exactly my issue, very thorough and clear. Ty! I was chasing my tail on and off for months

[@acservicetechchannel]

Glad to help Rigor!

[@alisaperry679]

best video I seen on flame rectification to ground

[@acservicetechchannel]

Thanks Alisa!

[@esbigerodeo1]

As always a good video. Your videos are great to refresh the mind. We have so much knowledge we have to obtain and store. A lot of times we may not use some of it for years,so needless to say we get rusty. That's why your video's are so great. Thank you

[@acservicetechchannel]

Yeah I forget things too. That is why being able to read wiring diagrams in order to figure out how something works and to remind yourself is so crucial, thanks Evan!

[@esbigerodeo1]

Yeah if someone cant read a schematic,they don't need to be in this field.

[@dporrasxtremeLS3]

Especially rusty grounds that can play frustrated thinking, getting to the next call too.

[@willardearl76]

Great video, had the same issue with a poor ground last week. Thank you sir.

[@acservicetechchannel]

Thanks Earl!

[@J0hnnyxm4s]

Excellent video; very easy to follow. I went through everything here and the only place I have a problem is low micro amps when the flame is on. I replaced the sensor but have the same issue. Would love to see a more advanced video of what to do when everything here looks good but you’re still failing the ignition proving test.

[@jpcooper78]

Probably the board, no?

[@J0hnnyxm4s]

@@jpcooper78 Sure, but what part of the board do you begin testing for this? Given the expense of (new) replacement boards, I’d love to see some board-level diagnostics. I grabbed a used replacement on eBay for $25, so it wasn’t worth the time of me figuring it out on my own.

[@jpcooper78]

@@J0hnnyxm4s well I ain’t quite smart enough to do board diagnostics, but I’ll tell ya this.. if I check the micro amps on the flame sensor and it’s 1 micro amp or higher the flame sensor is good. Check it to ground and if we have the same micro amps the ground connection is good. If we verify those two things are good and we know our gas pressure is good then the only component left is the board. At that point I can say with 100% confidence the board is bad. I’ve seen it a few times now in my career

[@chinoballa760]

I’ve seen the crimp connector holding the male spade onto the flame probe have corrosion inbetween the connector and probe. This will give you low amps. Same with any loose connection. Higher resistance across a connecting point will result in lower amps

[@mygripe]

Wow..thanks for the in depth video. This video is a keeper for future test

[@acservicetechchannel]

Thanks a lot!

[@dporrasxtremeLS3]

I watch these videos many times just for reminders before I get out on calls.

[@lucdumouchel3864]

That's where my problem was. Thank you

[@acservicetechchannel]

Great to hear the video helped!

[@JuanTodoli]

Good explanation to common problems.

[@acservicetechchannel]

Thanks Juan!

[@davidmarler7]

man I love your teaching skills. I can really only learn from certain people. not that I do not thank everyone that's taking there time to do this. but you get to the point and have your own way of doing things .I had a furnace problem it was text book gas valve flame rectification .well all day of going back and forth it was loosing 24 volts at gas valve it was jumping to 21 volts so after remembering your tstat video's I took condenser wires and tstat wires off .jumped the red and white to call for heat . .fired rite up the old thermostat had dust and some how shorted the 24 volts to like 21 volts .NO WAY I COULD HAVE FOUND THAT WITH OUT YOU TEACHING ME .THANK YOU .,BY THE WAY ON THE NEW (white Rodgers ) SINGLE STAGE GAS VALVES TERMENALS. honeywell replacement for ruud. ARE NOT MARKED .does it matter what wires you hook to what as far as old 24 volt wires it was from (pro tech)

[@acservicetechchannel]

Actually it may as this is where the common wire may be attached to the ground frame of the valve. What model number is it?

[@acrepairnearme]

Great video. Thank you. Why if I have only 50 volts AC. One lead on the plug hole for the flame sensor another is on the body of the furnace? Rhhem criterion II. Spark ignition furnace.

[@eovalle594]

just had a call earlier where I changed flame sensor and still not working and this just reminded of a ground issue on a furnace last year but didn't know could test with meter like this thanks

[@acservicetechchannel]

Yeah, it's usually the flame sensor is dirty, dirty retention head, bad grounding from the burner retention head to the board or bad ground or common to the furnace. Thanks Erik!

[@eovalle594]

acservicetech......I just went back out and made sure ground was good and seemed to be but when I tested the sensor I was at 1.5 milliamps is that good or bad could it possibly be my board or pressure switch aaahhh lol

[@acservicetechchannel]

Did you blow out the condensate lines during the service? Did you check negative pressure readings going to the pressure switch? I have found many furnaces intermittently working do to the condensate clogging up which makes the pressure witch open. Was there any error codes or did you pull up any old ones? What model # furnace was it? Is it broken when you get there or up and running? Right after it goes off are you checking for 24v across the high heat sensor wire and also the pressure switch 24v? Thanks

[@eovalle594]

acservicetech when got there flame sensor black exhaust had wasp nest clogging up tomorrow gonna change pressure switch also haven't tried blowing out the condensate lines I have unhooked though my voltage except flame sensor which is reading 1.5 micro amps grounding seems fine but gonna recheck.next gonna reverse polarity on my line wires see if that helps sensing the voltage on flame sensor. I know probably something simple think I'm getting old and forgetting some things lol and thanks a bunch

[@acservicetechchannel]

Glad to help, also clean the front of the flame retention head on the burner then too if there is soot from the wasp nest clogging. That could be stopping the dc micro amps.

[@frankduarte7109]

Would you check dc micro amps first or see if the flame sensor is getting it’s AC voltage from the board first

[@meerscan9101]

great video, your making it so easy for the new guys to learn the trade, just as david jones hvac/electrical says: pay it forward

[@meerscan9101]

do a 5,000 subs or so tool giveaway and you'll jump subscribers instantly

[@acservicetechchannel]

Absolutely always try to pay it forward.

[@acservicetechchannel]

Thanks for the contest thought.

[@joemartinez6806]

straight up many times Thank you sir. helping us save lives.

[@acservicetechchannel]

It really is a very serious thing so we need to know what we are doing and if we see a hazard. Did you check out the heat exchanger video. That one didn't have a flame rollout switch in the right spot and the earlier versions only have one.

[@papajoe3832]

acservicetech. Fantastic video sir! U make seem easy! Our HVACR tech instructor has not importance of always checking the integrity of the Flame sensor microDC amps return path btwn the burners and board connection. If I may respectfully, one tech hazard observation I believe you alrwady know but for the sake of example. Noticed a ring on left hand 4th digit w/ energized circuitry. Over the years I've shook hands w/ a few electricians (no HVACR techs yet though) missing fingers. I find challenging to remember to remove my many decades old wedding band. Anyway in the name of "safety first" figured U understand. Best wishes for 2017! Probst!!

[@acservicetechchannel]

Yes Papa Joe, I have often times have thought of just getting a tattoo ring but I refuse to take off my wedding ring. I always teach in a way where you can diagnose problems without much amperage going through components. I show everyone with 24v and resistance for the most part and amperage readings with the clamp on then turn the power on for safety. I do know what you mean. Thank you very much!

[@joemartinez6806]

papa joe yes, I Alamo know of rings causing great harm..

[@papajoe3832]

acservicetech. Certainly appreciate the devotion to your wedding band sir. I now recall past electrical safety practices you've demonstrated and should have noted. In fact U are the only YTube HVACR info tech I recall advocating use of gloves and one-hand multi-meter use w/ energized ckts. Thanks for response.

[@EnjoyCalculus]

is a potential difference between neutral and ground basically a short?

[@Stankuzak]

I was getting an attempt for the gas furnace to start and then quit going into lockout. I cleaned the flame sensor and reinstalled it with no difference. Meter is series with the flame sensor provided zero dc miro amp reading. Replaced the electronic board and the furnace is working great. The board is one of the top 5 things to go. It was on a Carrier Gas Furnace. So if you are getting no DC miro amp reading back when the meter is in series with the flame sensor and the flame sensor has 110 volts, it is probably a bad board as it was in my case.

[@AlexLopez-xw5jk]

Awesome Video! Thank you so much!

[@acservicetechchannel]

You're welcome!

[@mark.r8900]

i understand the micro amp going back to the control board on the ground wire. but what generates the 3.5 micro amp going into the flame rod? the control board is sending 90 vac to 110 vac into the flame rod and at the same time the meter is reading 3.5 micro amps. the voltage going into the flame rod is AC but the 3.5 micro amp is DC. please help me to understand this. thank you.

[@acservicetechchannel]

The micro amp reading is from the resistance or work that is being done while the voltage is traveling through the flame. AC is positive and negative. DC is just negative going to positive. DC amps are measured on the ac line because that is where it is coming from. I understand completely that this is an in depth and hard to understand flame proving method but it sounds like you are understanding, thanks Mark!

[@mark.r8900]

thank you again acservicetech.

[@petesingh292]

Hi great video, how about if u get 95volts at the flame sensor but there’s no Dc current of 3.5 ma

[@SombraLocs]

Great Great video! Very educational.

[@acservicetechchannel]

Thank you very much!

[@ericgroupe6383]

Was wondering if you had 125v from L1 to the common on the hsi and then measured say 123v from L1 to the ground those 2v could interfere with the signal back to the board what would be the best way to fix this ? By running a decicated ground wire from the burner box straight to the ground rod at the service panel? Thanks

[@habanalibre7275]

Thanks again, excellent class. Thanks so much. I agree with you, this electric tester is excellent.

[@acservicetechchannel]

Thanks Eduardo. Yes a lot of techs are using meters without all of these needed functions.

[@vincentsearle665]

does that mean there is always voltage present? That would make it much easier to tell when you have a bad board. I thought you had to have a call for heat. I have hydronic heat in my house or i would check out. Will do on a service call next time AC Service Tech LLC 3 years ago Yes while power on and no call for heat, test voltage common or ground and the other probe on the wire leading to the flame rod or the flame rod itself. Depending on the model this could be 90-120v ac usually, thanks

[@evanweller]

I dont think I have tested neutral on the ignitor to ground to look for voltage, what would cause that draw if that were to happen?

[@henrybartlett1986]

Excellent.

[@acservicetechchannel]

Many thanks!

[@moonlightacmaintenance3232]

I have a few questions. When testing ground wire was your black wire from meter shoved into mounting hole where green wire was mounted ? Also, if voltage was found on common to ground what are the potential problems and solutions ? If micro amps are found in sensor and ground to board does that point to the board ?

[@Alan-fr9uk]

Hi Craig, I see a lot of videos on cleaning, servicing, and troubleshooting flame sensors. The only problem I see is whether it is imperative to have the power turned off at the furnace before you work on this item or not. If 90v to110v ac (or possibly more) is coming from the circuit board, isn't it possible to be shocked or even electrocuted if you touch the sensor rod or an uninsulated sensor connection and your hand touches a grounded part of the furnace? Would the circuit board get fried if the energized sensor rod touched any part of the grounded furnace? Is the flame sensor always energized when the furnace power switch is on, regardless of if the furnace is in the heating, cooling, or off mode at the thermostat? Thank you for all of the great videos. They sure are a great help.

[@mark.r8900]

hi, at (2:50) the reading was 3.5ua. this is the current going FROM the control board into the flame rod? and on the ground side it's the current going BACK to the control board. is this correct? thank you.

[@acservicetechchannel]

Yes, sometimes you cant check the ground side due to the connection and the use of it being a common at some points, thanks

[@justomontero7231]

thanks for great video. one question when micro dc volts from the flame sensor are back to the board, how is the board analyzed it to keep the gas valve open, and why is that green /yellow wire with blue common in the gas valve doing

[@hinojosa552]

I have a question , if the flame sensor has been installed , but the microamp reading is 1.5. It's still good reading, or too low ?

[@replayreviews6339]

Question: During the ground test at about 5:50 did you screw the ground screw back into the unit and clamp your alligator clip to it?

[@acservicetechchannel]

Yes I believe that was what I did thanks

[@papoloco34]

Nice video like always!!!

[@acservicetechchannel]

Thanks Pedro!

[@Kiddro22]

This has to definately be my problem. Getting a E270 error code on a Lennox Elite model. Says Flame Current not Sensed. Replaced the flame sensor and ignitor and still it turns on then goes out. It tries five times then goes into Watchguard mode. Cleaned the old flame sensor and all. Still nothing. So this has to be my problem

[@Kiddro22]

UPDATE: it was my board. Replaced the board and the unit runs.

[@juanorduno1784]

Very good Video

[@acservicetechchannel]

Thank you Juan!

[@sergiogarcia5822]

Thank you for your videos, I learned a lot.

[@acservicetechchannel]

Thanks Sergio!

[@josepeixoto3384]

a little hand drawing on paper would have helped, i didn't quite get it; the probe has 100 V, then 4 uA, you measure where?

[@dennisnoone7427]

nice video, what would be a causes if readings some voltage between a common and a ground? thanks

[@acservicetechchannel]

Great Question. This would be if a hot somewhere is touching a ground but not enough to pop the breaker, This would be if a hot somewhere is touching a common but not enough to pop the breaker, bad main ground connection including over to the rod or rods, bad connection in the breaker box from ground to common.

[@phillipjoy8191]

Great video. Can you read the voltage that the board is sending to the flame sensor? I had a 80% Rheem gas furnace that would not read micro amps when the flame was present,so I cleaned the flame sensor and still no micro amp reading when flame was present. I went and got a new board and solved problem.

[@acservicetechchannel]

Yes while power on and no call for heat, test voltage common or ground and the other probe on the wire leading to the flame rod or the flame rod itself. Depending on the model this could be 90-120v ac usually, thanks

[@TheRepairGuru]

Thanks for the detailed info. Question - If the spade to the flame sensor is not insulated and you grab it like that and touch ground with your hand you will get a 110 volt shock correct?

[@acservicetechchannel]

correct

[@Guyhakverdi]

Could you please show how to check that voltage as you mentioned 80-180V? Is this voltage reading to ground or neutral ?

[@Guyhakverdi]

Will flame sensor short if touches to ground? I have seen someone on KZbin scratching flame sensor to ground and no short no arc or anything. Why this voltage does not discharge when there is direct contact? Do boards have any safety feature preventing this ?

[@Mowers11]

I appreciate the detail you go to when doing these tests. I really like the subject of furnace diagnosis. Kind of a junkie here but that is ok is it not?

[@acservicetechchannel]

The more you know, the more valuable you are so get as much knowledge as possible. I always wanted to know as much as possible about all the construction trades. I think as you strive to know more that is a good thing! Thanks for your comment Brian!

[@ericgroupe6383]

Be great if you could do a troubleshooting video on the 3 wire pilot ign system thanks

[@acservicetechchannel]

Thanks for letting me know what you would like to see!

[@seshachary5580]

very educative. still struggling if 110 volts goes to flame rod how does the circuit gets completed ? and how does ifc knows the microamp reading . can you kindly draw a circuit diagram. thank you regards, chary

[@acservicetechchannel]

Hey Sesha, It is not so easy for me to draw a diagram but the 110v would be present at the flame rod. Then the ac voltage can only go in one direction through the flame, rectifying it into dc sine it can't alternate back and forth. Then the dc microamp signal travels to the burner retention head or pilot if equipped, then to ground. It is picked up by a green or green with yellow stripe wire that also usually connects to the gas valve and possibly the combustion chamber. Then this ground wire travels back to the board in the green wire, thanks

[@seshachary5580]

thank you so much. great teaching. regards. chary

[@Texas_JohnQ]

Thank you for this, very informative.

[@acservicetechchannel]

Thanks!

[@NattyGirl134]

Hi I am having the same intermittent issues. I have clean the flame sensor and am getting the proper amount of microamps when the meter is in series. I have checked the resistance from the ground on the burner assembly to the flame sensor and was getting .4 ohms. I have checked the voltage and I do notice there is a voltage difference of .6 VAC between the hot and the neutral is this enough voltage difference to create the intermittent problem? I am running out of options and don't know what else to look for. When this problem first started happening I noticed the flame sensor wire was pinched between the flu and the burner assembly and was charred but not to the point that copper was showing I fixed the wiring and the problem has never ceased. Thanks for any advice.

[@SombraLocs]

@ 5:10 Where's do you have your black lead hooked up to?

[@acservicetechchannel]

The black lead is hooked to the ground screw that is partially screwed in where that ground wire screw was before.

[@nlowman83]

@@acservicetechchannel so if i'm understanding this correctly..... the micro amps that the flame proving rod generates is returned to the board first and then it is released to the ground wire that is connected to the cabinet......so if you have a loose ground wire the board does not register that the flame is present and shuts the gas valve off.

[@tmt4768]

Thanks brother!

[@kendalthompson3606]

Good video learned alot.

[@acservicetechchannel]

Thanks Kendal!

[@mark.r8900]

Hi, when I test microamp on the ground side I don't get any microamp. But the furnace still runs. Furnace is a lennox g61mpv with a low flame sense error code. The rod is clean, I am getting 3microamp going into the rod. But nothing coming out through ground. When I disconnect ground wire from burner box error code gone and furnace works fine. Please help thanks.

[@ryankinkade4246]

What could be the problem if you're readiing the microamps at the sensor and it goes from 4 to 12 to 20 and then the system shuts off at that point?

[@weibop6565]

My multi meter doesnt have the clip and for thr life of me i cant find my other rods. Could i use a paper clip? Or should i go buy new rods for my meter? Ive been systematically trouble shooting my entire furnace for the last week and every time it seems like its good to go ill come home and something will be going on sobim feeling now that it has to be one of these wires haha. Sorry to bother you my friend thank you for the insight

[@mojopinish]

Thanks for the video! How does a Miller M1 furnace sense flame?

[@acservicetechchannel]

I believe that has a flame rod for for gas and senses on the ground to the board and for oil it would have a cad cell, thanks

[@b-riair9114]

I had one today that would run for 5 mins at 2.7 micro amps to 3 micro amps then shut off.. start again and run 3 to 7 mins then off. I played with wires couldn’t get it to happen and the ground tested good with a clean flame rod.. it’s a 20 year old furnace I figured the old white roger replacement board that was put in several years ago was at fault does that sound like a board issue. I pushed and pulled the wire for the flame rod with no issues but moving the plug on the board seem to shut the burners off once in a while

[@acservicetechchannel]

Are the burner retention heads clean? Is there a ground wire going from the combustion area back to the board or is the ground wire back farther? Is the flame rod fully immersed in the flame? thanks

[@b-riair9114]

AC Service Tech LLC the ground for some reason came from the board to the transformer screw but was a clean surface. The sensor was enveloped in the flame with clean burners. I’m wondering if running an extra ground wire to the burner area would resolve the problem. I figured the circuit board was dropping the signal.. I know York diamond 80s are notorious for bad circuit boards.. they’re not going to repair the furnace since it is 20+ years old

[@SombraLocs]

Brian AcH-V-AC Did you resolve the issue?

[@b-riair9114]

Familia Sanchez HVAC it was the circuit board and they didn’t wanna replace it

[@dailygrindism]

Brian AcH-V-AC awesome 👏

[@alex83h]

What if I am reading the correct micro amps reading on both the flame sensor and ground? Does that mean the circuit board is bad?

[@alex83h]

Just want to add that my electricity was off for about 2.5 days with all this snow in Texas. Got power back but the heater won’t work. I get the flames for about 5 seconds then it cuts off.

[@janericchannel4513]

what should the voltage be going into the flame sensor? I get the mA measurement but I thought you still need to check the voltage going into the flame sensor.

[@acservicetechchannel]

This will depend on the system but it can be anywhere from 80 volts to 180 volts ac but usually it is 90-110volts. The flame rectification 110v is always present just in case there is a flame, thanks

[@ericgroupe6383]

Just wondering also in regards to this video if a few volts are found on the ground circuit what's best solution? Run a new ground wire or look for the resin you have voltage leaking to ground from L1 Supply sides thanks

[@acservicetechchannel]

It is usually bad ground to the breaker box, thanks

[@geojor]

thanks for this ...

[@acservicetechchannel]

Thank you!

[@avm5717]

is the microamp reading constant throughout the on cycle of the furnace?

[@acservicetechchannel]

Once the furnace has fired, the microamp reading should be roughly the same unless a different gas speed is energized in which case it will change slightly do to the amount of carbon and ion changes. It will remain very close though.

[@patricksullivan155]

So please tell me where you are allowed to use that galvanized pipe for gas? Best Practice will be toeducate the customer and change it out. Just my 2c

[@acservicetechchannel]

Hey Patrick, in the IFGC it does not differentiate between black iron and galv. You can use either unless for whatever reason your code inspector is using something other than the IFGC. Here near the ocean, you will fail your inspection if you use black iron. I am located in southern NJ. Anyway, its kind of funny. It really is just your local inspector and their interpretation or how they feel. There is nothing anywhere on the books that I am aware of that says you are not allowed to use galv. Once again, where I am located at, supply houses will not even stock any black iron whatsover not even for boiler trim since we are near the ocean. If you move 1 hour inland from my location, supply houses will sell black iron and inspectors allow it. Funny huh?

[@patricksullivan155]

@@acservicetechchannel and your code says that you can mix the 2? Strange. Again look into the practice and maybe you won’t chose the cheapest rout. But hey you do you. I would recommend looking into the effects and make better choices as the educated mechanic.

[@jamesspies630]

thank you!!!!

[@acservicetechchannel]

Thanks James!

[@hinojosa552]

Ok I take it back. I had the meter set on microamps

[@rocker8692]

can you be electrocuted if one lead of your meter is on hot and you touch other lead of meter with your hand?

[@habanalibre7275]

A cuestión. Do you have some video about limit switches?

[@acservicetechchannel]

This video is on testing the high heat limit switch otherwise known as the high heat plenum switch --- kzbin.info/www/bejne/mJrcpHarpaicZs0

[@OcRefrig]

Good Vid.

[@acservicetechchannel]

Thank you, and thanks for what you are doing for up-and-coming techs!

[@SombraLocs]

What if you have too high of a resistance from your burner to ground wire on molex plug that connects to circuit board.

[@acservicetechchannel]

You would need to run an additional wire from the burner piping screw to where that molex plug connects to ground, thanks!

[@seshachary5580]

should one wire brush the front face of burner periodically as rust can built up with water as byproduct of combustion. this rust may reduce the microamp. from the flame sensor. thank you await your response. thank you

[@acservicetechchannel]

Yes but so you know there are only so many years that you can brush the front of those to clear the rust in the passageway from one burner to the next. We see this problem more so in outdoor packaged heaters. After about four years of rusting and brushing away the rust they need to be replaced. On a standard split system indoor furnace you can get away with more years, thanks

[@seshachary5580]

thank you again.

[@briangulseth4564]

hello out there. I bought a goodman 96 percent furnace and installed it runs but it does the short cycle but not all the time I have checked all the grounds in the furnace all the connections are tight and are on bare surfaces it will run until is satisfies the thermostat the burners are clean and the flame sensor is clean the furnace isn't even 2 weeks old. can the flame sensor work intermitted and still be faulty or does it sound more like a ground problem. the other thing is the power coming on the furnace the wires coming into the switch should there be a ground to it and from there to the furnace the way it is right now the ground wire just comes straight in. ground is ground right? what would be the way of checking the ground to the furnace. thanks for reading

[@briangulseth4564]

also are you touching the probe on the burner

[@acservicetechchannel]

The flame sensor doesn't really go bad for the most part. It just puts ac voltage into the flame. That is its only job. The board sees the dc microamp current on a separate ground wire to the board. You may need to find where this green wire goes into the board at and where it connects to the ground of the furnace. It may be on the gas pipe bracket leading to the orifices. You may want to also check if the pressure switch is dropping out. That is one of those intermittent issues that has to do with the condensate. I would look some of those videos up too but not sure if any error codes are coming up on t=your furnace, thanks

[@briangulseth4564]

@@acservicetechchannel figured it out today it was a fuel pressure problem ty very much for you time

[@boris31067]

Hi acservicetech video is great, I have a good man gas furnace 80, this is what is doing inducer motor run, pressure switch close, ignitor turn on cherry red, gas open and turns off so I checked flame rod 0 microamp, ground wire 0.5 microamp so I replaced flame rod and it did the same, checking wires at the board found some wires loose I pushed them in and the LED red light turn on and off so I replaced the board, some help, I cant figure it out was wrong.

[@acservicetechchannel]

Is this pilot ignition or direct ignition?

[@boris31067]

acservicetech hi, it is direct ignition

[@acservicetechchannel]

Check to make sure that the burner retention head does not have soot on the end of it. Make sure the flame is fully enveloping the rod and that the flame is pressure is good. Check the grounding or do a trial jumper connecting the ground to the combustion chamber where the burner retention heads are attached. You also should be able to see dc microamps when your multimeter is in series with the flame rod if it is being rectified by the flame. Also make sure that 80-180v is going to the flame sensor. Check all ground connections and tighten. Make sure that the line voltage ground is good, thanks Boris!

[@zoidelux]

Can you get shocked by touching the flame sensor if energized? They operate on 120v ac ? But have so little amps? Please correct me

[@acservicetechchannel]

Absolutely don't touch any live wires such as the flame rod or flame sensor. The rod is live anytime the furnace is on, thanks!

[@zoidelux]

So, I have a intermittent flame sense problem... I think it might be the flame sense control going bad? Im getting huge fluctuations in microamps when i have the flame rod in series w my meter... Like it dips down to .5 and as high as 4 or 5 uA.... I tried a brand new flame sensor and it did the same thing....I monitored the boiler almost all day today with no hiccups, then i left for an hour, came back and its back in flame sensor error lockout. Its a very old boiler, Honeywell flame control. Any thoughts? Do you have a donation thing set up for advice?

[@acservicetechchannel]

Hey Ryan, I would check the grounding connection as that is what brings the micro amps signal back however as you said, there is some fluctuation in the microamp reading. Here is the paypal account for donations if you want to support the work of this channel- www.paypal.me/acservicetech - also I have a patreon account for those that want to show continued support and receive articles and some videos as well as have continued questions answered on an ongoing basis- patreon.com/acservicetech - Some things to check before replacing the control- Check to make sure that the flame rod is indeed getting 80-180v going to it. Make sure the flame rod is cleaned with steel wool. Make sure the ground wire coming back to the board is connected well at the board and at the ground frame. If you have a pilot tube then make sure the tube is tight in the gas valve as this is your flame ground if you have a pilot. Make sure the ground pilot tube termination or the burner tubes are clean as this is where the flame connects from the flame rod to the ground to send the dc micro amp signal, also make sure that the flame is large enough to connect these two the flame sensor and the ground especially if we are talking a pilot, thanks

[@zoidelux]

acservicetech thanks for the tips... Thanks for your video too, its nice to have a deeper understanding of this stuff. This pilot assembly has a ground wire attached to it going back to the controller, i put one lead on the controller ground, and one lead on the pilot assembly where the flame is and im getting 1 ohm... And u did clean the flame sensor really good as well as try a brand new one. Tightened and cleaned connections... But i think its the controller because i can hear the relays making weird sounds around the time it fails... Plus the microamps reading is all over the place . Shouldn't it be a steady uA reading? And yes there is about 188 volts ac at the sensor rod

[@acservicetechchannel]

Yes the uA reading should be steady and the 188 volts should be steady. As long as you made sure your connections are good and you have a good flame that is not flickering around at the pilot but making sure there is good consistent flame from the rod to the ground then you are ready to order the board, thanks Ryan!

[@seanmcdermott416]

Whats is the difference between micro amps and milli amp ? And in which application would I use milli amps as a unit of measure for troubleshooting ?

[@acservicetechchannel]

Hey Sean, a Microamp is 1000th of a Milliamp. We use millivolt readings when checking 750mv thermopiles and 30mv thermocouples. Not really too much in milliamps though in troubleshooting, thanks and here is a playlist on ignition including mv- kzbin.info/www/bejne/p5vVo4ujgdF_iMU

[@ModifyThis]

Rheem RGPH-07EAUER: From the ground side, I cannot register any DC uA. I do though get 3.00 uA on the source side. I confirmed the signal wire from the IFC board to ground is 0.00 ohms, and checking the common to ground I get 0 vac, so what could be causing this? Is it normal when testing the flame sensor for voltage, to get only 6 vac, b/c it seems pretty low? When I do this test, it also causes the blower to come on and the unit reports an Unexpected Flame is Detected. None of this seems normal to me, I would love to hear from someone their thoughts regarding this.

[@acservicetechchannel]

You should get anywhere from 80 volts on some systems all the way up to 180v with the smart valve when reading voltage from the flame sensor wire to ground or flame sensor to 120v common. Normally with control boards the voltage is 90-110v. disconnect the flame sensor wire from the flame sensor and test the wire by itself. Then pull the flame sensor wire out to make sure that it is not touching a ground somewhere but typically it will still be connected to a pin connector at the board. Test the voltage as close to the board as possible. By the way, i this electronic spark ignition? If you still don't get the correct voltage coming off the board to the flame sensor wire and if you don't have any voltage drop on the furnace when the furnace is trying to run and if you get the same voltage reading at your furnace from hot to ground as you do hot to common when the furnace is trying to run then it sounds like a bad board, thanks

[@Guyhakverdi]

Did you figure it out ?

[@jonathanraul4086]

Ty

[@acservicetechchannel]

Thanks Jonathan!

[@originalCN4]

I had no idea flame rectification existed, things have come a long way in regards to furnaces obviously

[@robertmalone9699]

Micro amps?

[@wasup23tube]

Why not just have them check for mvDC? You don't have to disconnect anything.

[@acservicetechchannel]

To check the micro amp level, the reading is taken through the meter in series. The micro amp number is what you are looking for. Thanks!

[@johnunderwood3132]

I cleaned the rod sensor and flame still goes out.

[@Kiddro22]

You might be going thru what I'm experiencing. Read my comment above or below

[@ajm9593]

How can a flame sensor "fail", since it's just a solid piece of metal? Assume it's cleaned off of any carbon build-up. Thanks!

[@acservicetechchannel]

Exactly, it won't unless the ceramic is cracked or it is a small sensor and is melted/bent. Exactly, its crazy how many flame sensors are sold to no avail!

[@ajm9593]

Uuugh. Which I just did! :-( So, I've gone through all the other obvious possible things that could cause short cycling, filter, flues, cleaned off the flame sensor, all the connections seem good, yet furnace is still short cycling. My next effort will be to see if I can get to and clean off the burner heads, especially the one in front of the flame sensor, but short of that working, I have no idea what the problem could be. What other component failure could cause short cycling? In my case, the furnace runs for about 3-5 mins before shutting off. Thanks!

[@Kiddro22]

AJM same problem I’m having

[@ajm9593]

@@Kiddro22 Turns out my problem was a malfunction of the sensor on the door that closes off the airflow when the unit is off. Bypassed that, so the door stays open, and no problems since! The door's only function, is to prevent a minute amount of cold air coming into the house from the flue, when the unit is off.

[@ajm9593]

I also had the main heat sensor fail, and replaced that. Super easy to replace. Easy to check with a resistance test. Can't remember now which time was which between the door and the heat sensor.

[@rayner1guerra]

Some body know how to replace the coil (WR) in this kind of valve? Y have one coil WR that have a hole in the plastic cover. The valve works but i want to replace only the coil. The other coil have the number, 36E01 257. other number 128927 other number in the label E08 9849. 24v 0.3 A.

[@replayreviews6339]

I love that I use the same meter lol not a fan of FP

[@acservicetechchannel]

I used the UEI when I started, thanks

[@melvin292]

Hey GUYS, this is ac service tech. What happened to the gals who are in this trade. Have you forgotten them?

[@acservicetechchannel]

I encourage young female students as well as young male students to pursue this awesome trade. When I say "Hey Guys this is ACSERVICETECH" in each of the videos, I mean everyone. I say that at school with a class of girls and guys in it and no one ever flinches. Funny enough I don't mean anything by it and most of the people in my area actually say that phrase and do mean all. Where I am located people accept it as meaning everyone. I think it is one of those sayings that is passed on that you get used to others saying even though it actually means something else. You are right, now that I think about it in the context of someone on the other side of the country or another country. I don't mean it as male only. My top female student won silver in the state hvacr competition last year!

[@melvin292]

+acservicetech well, please do not think my words are criticism. Even Holy Bible we study here in the states makes clear when "he" is use, the Holy word is referring to all mankind. You are very generous with your kindness and wisdom. All who learn from you appreciate your dedication to the youth of tomorrow. God bless you and keep up the excellent videos.

[@acservicetechchannel]

God Bless you too, and awesome that you just referenced the Word!

[@rodgraff1782]

I dont think the flame rod is getting sent 90 to 110 volts like you say, otherwise when i short it out to ground with my hand to see it drop out i would be knocked on my ass.

[@franciscrasto]

If it is direct short it will blow the fuse. but he talking about the ground wire which is having bad connection hence no full voltage on the flame 🔥 sensor

[@MrPaulrak]

Micro amp? Try Milliamp.....

[@acservicetechchannel]

The amount of Direct current measured during flame rectification is Microamp not Milliamp

[@HarryIrvinecommericalacrepairs]

This was a great video. I did not know that if the ground wire is not connected the flame sensor will not work, this is what just happen to me today, I will try this tomorrow.Thank you for this video it was very helpful.Harry Irvine www.californiaac.com/spotcooling.php

[@acservicetechchannel]

Thanks Harry Irvine!

[@joeyravage4798]

.....heh.heh.....hehheheh.....”screw holes”.... heheheh........

[@acservicetechchannel]

Some furnaces have a hard time with the ground being continuous through all the components and need help from the ground wires which solves the intermittent loss of the dc microamps, thanks

[@spartan5106]

I didn't understand anything 😮‍💨😮‍💨😮‍💨