Troubleshooting the Furnace Control Board IFC to Test if its BAD! For Heat and AC Diagnosis!

[@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 for the Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Here is the link to the newer UEI Dual Pressure Testing Manometer- amzn.to/2y5lzVF Here is the link to the Fieldpiece SDMN6 Dual Pressure Testing Manometer with Pump-amzn.to/2jyK5Ka Here is the link for the Rectorseal SS2 condensate float switch- amzn.to/2itk7nk Here is the link for the Rectorseal SS3 condensate float switch-amzn.to/2jkry4X 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.

[@jamesmelody6960]

acservicetech m

[@ds132100]

@acservicetechchannel I was watching your video because I’m not getting 24v to my thermostat and I’m thinking it’s a bad board but why am I not getting 24 v if my transformer is working fine ?

[@vernroach3413]

As a former journeyman/service/installer and HVAC instructor and now, soon to be instructing again, I can say this is excellent instruction...Clear, easy to understand and well done...Kudo's to the gent that make it.

[@acservicetechchannel]

Thank you very much Vern. Where are you going to be teaching now?

[@ronnyrath816]

Hands down the best HVAC teacher I ever come across. By watching ALL yours videos, it made me a better technician. From my heart. Thank you sir.

[@acservicetechchannel]

That is really encouraging Ronny! Thank you for taking the time to write the note!

[@tomwest2926]

Thank you!. I watched dozens of videos, YOURS WAS THE KICKER! Had 4 flashes, and the blower motor was not delaying. Checked the air switch and temp switch, repeatedly. I was convinced it was the relay and was ready to buy a new board. In the end just a loose connection at pin for air switch. Thanks again!

[@Mowers11]

One of the best videos on KZbin for IFC sequence of operations I have seen. Grayfurnaceman is good but for the most clear info on IFC in one video this is my bet. GOOD WORK, sir. I will use your video to do my exploratory IFC work.

[@acservicetechchannel]

Thank you very much for your kind and sincere comment!

[@seanmcdermott416]

A.c. your service lessons are G.O.A.T . Instead of calling in for tech support I take a few minutes and watch one that I saved on my phone . Problem solved ! I get my calls done faster and I leave the job not stressed out on my way to another. Thanks man

[@acservicetechchannel]

Ha ha, I am glad the videos are helping and letting you have a bit of peace, thanks!

[@josephgoodman7989]

You are the man 👨

[@kingtut6401]

Thank you so much...I was losing my mind. The control board had zero led flashing messages & was working as it should. The problem I had was everything worked but the gas would not shoot out my two stage valve. So I replaced it to be safe. Even on the new valve I got 24 volts on the high second stage but zero volts on the low side of the gas valve. Meaning I had a fault somewhere per my wiring diagram on my Goodman 2 stage furnace.. I replaced everything...flame sensor, pressure switch, rollout switches, hi temp switches. I was now zeroing in on the control board. So I watched hours of videos and finally found yours that actually troubleshot the board in detail. I pulled the clip on the board out that held the 12 wires. I found the one from the pressure switch was loose and push it further inro the clip...I clip it back in...and was thinking yeah right that aint going to work...I push in the safety off switch. The furnace did it's clicking as it should and right at the moment the glow plug was ready to go out BAM..the gas finally came out the manifold....ME SO HAPPY thanks...I was dreading calling the repair man on Monday even though my family was freezing their asses off and making fun of my handyman skills. Goodman - Model GMH80905CNAB -2004

[@acservicetechchannel]

That's awesome to hear and an encouragement for me, thanks!

[@kingtut6401]

@@acservicetechchannel Actually it was the control board....after 30 minutes I got the pressure sensor error 3 flashes now...So I shut if off did the old school finger flicker on each relay on the board and turn it back ON....started right back up again...I will monitor it. Probably replace the board now, now at least everything will be brand new again.

[@danieldummett3731]

Hey just wanted to say your videos are absolutely amazing. so thorough and clear. Well done man, well done.

[@acservicetechchannel]

Thanks a lot Daniel Dummett!

[@topdoted]

Wish I had looked at your videos before calling someone out who said I had a bad board. It wasn't the board. After watching your videos, the light bulb came on and I figured out that it was the thermostat all along.

[@acservicetechchannel]

Glad to hear you enjoyed the video!

[@dyershvac5884]

Excellent videos! Definitely 1 of the best in my book! Keep up the great work. Teaching alot of people how to do it right.

[@acservicetechchannel]

Wow, thanks!

[@capitolrefrigerationheatin7501]

thanks for the in depth walk through of how the board works, i have seen some experienced techs misdiagnose boards, excellent posting!!!!!!!!!!!!!

[@acservicetechchannel]

Thank you Capitol!

[@tomwinds9729]

Clear instructions and crisp video. The best I have found so far on the web. Thanks.

[@acservicetechchannel]

Thanks Tom!

[@squidusn71]

I don't know anything about electrical troubleshooting especially on a circuit board but this made me a little bit smarter.

[@jx5173]

Hi. First, thank you for sharing your knowledge. Everything I write here was learned by watching your videos so don't be misled, I'm not experienced in HVAC. I'm a homeowner with a limited budget and a non-working furnace. What I'm trying to do is diagnose and/or do as much as I can before calling in a pro. I do that with all things mechanical because there are a lot of dishonest people that see dollar signs when a woman calls. I hate that. Problem: inducer won't power on. LED blinking 3x = pressure switch open. A/C and blower work, both together and on fan alone (new blower in 2017). Using multimeter, thermostat and pressure switch test good. Testing out from board, inducer wires read: 18.7 ohms, 0.0 volts. That leads me to believe the board is bad (?). My questionis is, is there anything I may have missed that you can see here, or am I likely correct? Board is White-Rodgers 50A50 110 (no fuse), furnace stickers read Comfortmaker RPJII. Part II (because why not?: If it seems like I'm correct with a bad board, is 50A55 843 the correct replacement? Thank you!

[@acservicetechchannel]

Not sure of the replacement board but if you call for heat at the tstat then you should have 24v between w and c at the board. If that is the case and you don't have 120v going to the inducer and there are no other error codes or blower motor is not blowing all the time due to a safety being open then yes that would be a bad fan relay on the board likely, thanks

[@jx5173]

@@acservicetechchannel Thanks so much for taking the time to answer. There was one other connection I overlooked for testing before I wrote, it's a round thing -about quarter-size in diameter-centered on the inside wall right under the inducer. Two brown wires, one joined to a red pressure switch wire. Pulled to test, switched power on and the blower started up, meter read 27v. So that was cool. Ran it like that for about 7 minutes but inducer never started and LED still flashed PS closed. Confirmed (in my limited education) the board. Writing this part really just to show you what you taught me. Oh, and the brown wires tell me the round thing is a capacitor(?). Can't thank you enough but I think you have a link posted somewhere that I can make a donation. Doing that for sure. Thanks again. :)

[@boosted2.4_sky]

This is my situation...same symptoms and fix.. thanks much...

[@ryanmorgan4090]

Common? I appreciate the videos, but so many people refer to common, when referring to a voltage, but it's also referring to a ground. Common hot, common ground. It has been a speed bump for many new guys. Great videos, I thank you.

[@hvacworkshop4791]

Some tech like to replace board to make more money. They can just say "the board is dead too". Nice videos.

[@acservicetechchannel]

Yeah that's no good. I think most of the time it is not on purpose but some just don't know what the problem is so they change multiple parts. Thanks

[@steveo7624]

I always review my trouble shooting skills.when your led light doesnt work check control board,when your furnace does not fellow the sequence of operation ,does crazy stuff like inducer motor working in cool mode check control board thanks for the review

[@amitshah9447]

You r the best teacher 👨‍🏫 Sir I salute you

[@rayb2078]

you by passed checking to see if the fuse is good along with the rest.... good video..

[@eman3208]

Another good video servicetech, thanks Man...

[@acservicetechchannel]

Thanks eman3208!

[@jon50harding]

Great video! Just replaced a board in a trane TUH last week, first one in a couple years or so and that's the problem I was having.. it wasn't sending voltage to my inducer

[@acservicetechchannel]

Thanks jon!

[@shawnmcauliffe5072]

Awesome detailed and step by step trouble shooting guide!

[@acservicetechchannel]

Thanks a lot Shawn! We have a troubleshooting guide for checking refrigerant charges in the new book we put out. The full outline is available at acservicetech.com thanks!

[@ronaldcach2779]

Hi great video, now I do not fear circuit boards as much. Could you do a video on slowly reading a wiring diagram [example- reading them step by step, and what it means THANKS FRIEND]

[@acservicetechchannel]

I do plan on doing something like this as others have asked too. Thanks for letting me know Ronald Cach. I always like to know what you all are looking for. Thanks

[@padilla7019]

Another great video. Very well explained.

[@acservicetechchannel]

Thanks Luis!

[@Nicholas-im8bd]

Ran into a York last week... Blower was shaking like crazy when I got there and randomly cycling with no error codes... After cleaning the blower, shaking stopped but still a random issue I went through everything in that furnace with a fine tooth comb. Testing everything and checking every connection. Even went as far by passing every limit and switch one by one in case I missed something with the meter. Ended up needing a board. Guess being shaken to death by the blower did it in

[@acservicetechchannel]

Was this a variable speed blower, x13, or a psc blower randomly cycling out of curiosity? Thanks

[@keithrichards6816]

Thanks for your videos you are doing a great job.

[@acservicetechchannel]

Thanks Keith!

[@melvin292]

Nice video. Great info and to the point.

[@acservicetechchannel]

Thanks melvin292!

[@MrOhiousa]

Another great video. Thank you very much.

[@acservicetechchannel]

Thanks MrOhiousa, I appreciate the comment!

[@jaredeby5344]

Thanks for in depth explanation, as a new tech this helps a lot! Will reference this again!

[@acservicetechchannel]

Awesome to hear Jared!

[@joemartinez2432]

Acservicetech for America's president.

[@acservicetechchannel]

Ha no thanks! Glad you enjoyed it!

[@tonymoran9794]

Thanks for the spark ignition foot note!

[@CT-Properties]

I have this same board. I'm getting 3 short flashes and 3 long flashes. My roll out flame switch is good, the limit switch is good, the fan motor capacitor was bad and I replaced it. I'm still not getting power off the board from the heat and com on the board to the fan motor. Would you say it's the board causing this problem? Also is there a difference between board 1012-940-L & 1012-940-J ?

[@MrFrozen73]

Very instructive video !! Thanks for your effort.

[@acservicetechchannel]

Thanks Hvac_jc!

[@mrofnocnon]

Good explanation but what of a failed blower timer?

[@waterheaterservices]

Very good tutorial

[@acservicetechchannel]

Thanks Jim Rr!

[@houakongvangable]

Followed your video and my hot surface ignitor is not getting 120V and does not have a resistance reading. Inducer motor works and pressure switch is closed per your tutorial and visually. Do the entire board need to be replaced?

[@ed_e_co]

I have a what looks like a diode that’s leaving a burnt mark behind it on the board, it’s also extremely hot to the touch! Is this normal?

[@HungNguyen-sb1yu]

My igniter lighted but the gas valve didn’t open. I watched your video and you said the 24v blue wire and the yellow common wire turn on the gas valve. Where do I place my multimeter probes on the control board to measure the voltage to the gas valve? Thank you.

[@scientist100]

My igniter lights up for a period of time but gas is lacking for the next step, blower motor activates for a little bit thereafter and restarts the sequence. I disconnected and checked voltage at the gas valve and the voltage was around 28vac for about 5 seconds. I reconnected the two pins to the gas valve and it was pulled down to 0.5vac. when the board tries to actuate the gas valve, I can see a slight change of voltage and then returns back immediately to 0.5vac, does this indicate a bad board or bad winding in the valve? Disconnected gas valve pins I read 15vac but when I connect it, it gets pulled down to about 0.5vac. Thank you for your help.

[@jiismo]

Just had the older version of this board fail. The mechanical relay for the 24V safety circuit was good. Relay sticky. new board uses solid state relay to eliminate that problem.

[@jaydwgtre0]

Great video!

[@therealtech833]

I have a furnace that the heat continues to run, heating the home to nearly 90° without shutting off. Replaced the thermostat already, no fix. A quick test after replacing the thermostat did not have any issues, both the heat and air turned on/off. However when it runs a cycle for more than a few minutes, for some reason the heat continues to run, without shutting off, even though thermostat is no longer engaged. Is there anything besides the control board that would keep the furnace running even after the thermostat says it's off and not sending the voltage signal?

[@jimmyung3212]

Very very very good details thank you!!!

[@acservicetechchannel]

Thank you jimmy ung!

[@univex1]

You mentioned reading the schematic diagram for this board. Where can I find the schematic diagram for this specific board? I've searched extensively but couldn't locate it anywhere.

[@skidscatt9892]

Absolutely wonder explaining my man! 👍👌 You've helped me so much with this man. Thank you

[@acservicetechchannel]

Thanks Scott!

[@ccautollc864]

Everything seems to be working properly on mine other than no power going to ignitor. Likely the board?

[@5822huron]

Excellent instruction

[@acservicetechchannel]

Thanks StraightoutofGeorgia!

[@MasterCoolSiemReap]

good sharing

[@acservicetechchannel]

Thanks for visiting

[@MasterCoolSiemReap]

@@acservicetechchannel never mind dear, i hope too

[@erice.5844]

PS.. to my current question on the 1998/ Tappan 92.1 gas H.E. furnace.... (just posted) did another test for a degree warmer.. 68 from 67..room temp. Cycled on and cycle off at 69.. also low speed of fan did kick on before shutting off. fan had a little whine to it.. thinking to lubricate it, as well! Let me know if it may be ok to use temporarily until I receive a new control board! Details in previous message just left... Thank you Eric MN

[@cheddymachete]

Where does the spark ignighter get 6000 volts ?

[@bonafide6464]

Great videos AC Jedi! Thank you very much!

[@acservicetechchannel]

Thanks Bonafide!

[@rickbraden4272]

If I understood you, you said if green has 24v then blower will run & if yellow has 24v you will have high speed on blower. I don't think so. Green is blower speed for ac along with yellow to run compressor for ac. Green is same speed when you turn Fan on at stat. The slower blower speed, usually for heat only comes on through heat cycle & not any stat wire like you said. Good video.

[@acservicetechchannel]

Hey Rick, I can tell you that on most systems with a board, when you have the fan on and you then call for cooling, the blower motor speed is adjusted to the faster of the two speeds. Systems that just have relays have the cooling speed match the fan speed, thanks

[@rickbraden4272]

@@acservicetechchannel thank you for clarifying that. Keep up the good work.

[@EEZYEEEE]

I'm not getting any low voltage reading from the wires that go into my thermostat. I also checked the reading at the board for RW, RY, etc., but not getting 24 vac. Fuse, breaker, drain, transformer, are all working fine. Any suggestions on what my issue can be? I'm not getting any power to my thermostat so it is just blank. I tried swapping thermostats but that didn't help.

[@jhon19753]

I have no idea what I'm looking at but we have this system in my house. A friend of ours who works in AC said that our board needed to be replaced. At the bottom of the board you see a bunch of letters and numbers, what is the difference in the ending letter of the first segment? 1012-940-L or 1012-940-J or 1012-940-M When trying to purchase one i found a hard time trying to find the L board.

[@druer_gsxr]

So to be clear and Im sorry if it explained, if any of the sensors are tripped OPEN will that cut off the 120v at the terminals of my inducer motor at the board basically 120v off the board terminal will it not read 120v?

[@carlossaenz4075]

I have a trane/American standard heater/ s8b1b080m4pacaa/ when I put on fan only on tstat it goes in the lowest speed. The manual says the speed can not be changed . I was told the round about to this is, take the y wire off the board that comes from the compressor. Also take the y wire off the board that comes from the tstat put them together ( wire nut then together) Now put a jumper wire from g on the board to the y on the board. And should take care of ur fan only problem. What do u think about this

[@DucNguyen-ww5xc]

Thanks for great video. I have a very interesting situation which i don't know the root cause. There is 24v going into the gas valve and heat is running fine. Certainly there is no voltage to the gas valve. I unplug the wires plug from the circuit board and plug it back and this time 24v are there for gas valve to turn on. If you know what is the problem, please let me know. Thanks for the help.

[@saeedhameed9148]

Thanks for another great video

[@acservicetechchannel]

Thank you!

[@lucasnino7810]

Hello good morning. I am asking you about a 62-24140-01 controller board for a Rheem heater. When I give it power, the green "OK" LED stays blinking permanently and does not perform any function. Could it be that it has any damage? I already checked the securities and with another board the equipment worked very well. Could it be repaired? Thank you for your time, Lucas greets you from Argentina! your videos are very good.

[@antonyfranco3219]

Hey can you please help me figure this one out? My furnace stop working and I noticed the board was making a fast clicking noise, I bought a use board from ebay and installed but still the same, there's 118v coming to the board 84v coming to the transformer and 17 coming from the transformer

[@mattzurzola4664]

Him and Grayfurnace man are the only TWO I TRUST

[@acservicetechchannel]

Thanks Matthew Zurzola! I appreciate your comments!

[@JustinCrediblename]

what if I'm getting .1v AC between the red and the ground? There's definitely 240v at the input terminals .. do these boards sometimes get fixed by cleaning them? It's the first time that I powered up the (new) package unit. [goodman] the board got rained on, but it wasn't hooked up to power...

[@MrRondeezzee]

Just found your video, I'm getting 3 blinks from my Goodman furnace . I changed the inducer, pressure switch and hose. Inducer had stopped turning, everything worked great for a month then I changed the dirty filters and it ran fine. Now im cycling but it doesn't fire up and I'm still getting 3 flashes. I bought a meter and I'm getting volts to the pressure switch but what I did notice is that the part that glows to ignite the furnace doesn't glow anymore. I used the meter to check for power but there's no voltage. Any idea on where i may go next? Just figured it out thanks for the video, I had power everywhere so I moved the wire on the control board and its running. Let it run for a few minutes and see how it goes.🤞🤞

[@madanmanish]

Thank you for your video. I replaced the 5 wire (assuming that had gone bad initially) but the system is still not turning on. The LED light turns on when I press the door switch but nothing else. Last night, I tried jumping the wires and it turned on. Can we deduce that the circuit board is bad or is there something else that I should be looking into? Thanks for your guidance! ps: I also changed the 3A blade fuse.

[@joshuadavis8854]

Awesome thanks alot pal

[@acservicetechchannel]

Happy to help!

[@HungNguyen-sb1yu]

Do you have a video how to know if the gas valve is bad? Thank you.

[@LarsonFamilyFarm-LLC]

Very helpful..thank you

[@acservicetechchannel]

Thanks a lot Accuracy Marked!

[@topc5826]

I've been watching all the troubleshooting videos but haven't found the answer to the issue I've been trying to resolve. On a Goodman propane gas fired hot air furnace, when the furnace is not in use for heat but you want to manually operate the blower to circulate air or the AC unit calls for blower fan, the fan does NOT turn ON, either by using the manual ON setting on the thermostat or the thermostat calls for cooling. However, I found that the pressure switch for the gas valve, which is normally OPEN, and it requires the inducer fan to be ON by drawing down a vacuum on the switch to CLOSE the contacts, the fan works. With the furnace OFF and the pressure switch bypassed and the two contact leads shorted together the manual FAN control on the thermostat WORKS and then I switch off the manual FAN setting and set the thermostat to COOL and then if I lower the temperature setting with the thermostat set to COOLING the fan will now come on when the compressor starts running. So how do I troubleshoot this to determine if it is not the control board, but some other component in the system? Where is the voltage coming from that is used by the manual fan switch control on the digital thermostat or the AC unit when it calls for Blower motor to run and the furnace pressure switch is in its Normally Open position?

[@anthonyellerbrock932]

The furnace turns-on, blower and exhaust fan and flame. It runs for about 60 seconds or so then shut off. When it shuts off, the thermostat goes dark. 5 minutes later, the thermostat turns back on and the furnace fires up. The fact that the thermostat shuts completely off, lends me to think it's the circuit board...perhaps a bad relay. Thoughts?

[@tonylowriderordonez7518]

Great teacher thank you

[@acservicetechchannel]

Thanks Tony!

[@137bob3d]

stimulating presentation.

[@acservicetechchannel]

Thanks Bob!

[@monterrozacesar5]

Very good video. Thanks

[@acservicetechchannel]

Thanks monterrozacesar5!

[@miguelloza4454]

All of your videos are great do you have a video of how to bypass a package unit control board with it not having a transformer

[@acservicetechchannel]

I have one on bypassing a heat pump for cooling if you look up those key words, thanks!

[@MrMazizo121]

Thank you for this knowledge!!

[@acservicetechchannel]

Thanks Filix!

[@ivanmurillo9072]

great videos.. always usefull

[@acservicetechchannel]

Thanks Ivan Murillo!

[@HungNguyen-sb1yu]

Please give me a link to your video on gas valve. Thank you.

[@RockoRocko-rz7kx]

Very detailed, however never herd anything about the low voltage 3amp fuse

[@acservicetechchannel]

Thanks, here is a video I did right before this one on the blown fuse, thanks - kzbin.info/www/bejne/oGirln93j7uHsNU

[@chickedwin7194]

God bless you once more sir. Pls sir what is the difference between the COMMON and the R wire on the furnace control board? Thanks.

[@acservicetechchannel]

Thanks Chick! The R is 24v power from the transformer and the C is the common path back for the voltage. Usually the common touches the ground as well but the voltage takes the path of least resistance back to the transformer, thanks!

[@chickedwin7194]

@@acservicetechchannel excellent

[@bryans8193]

First of all great videos and thank you for them! I'm having a problem with my AC. Intermittently when my system calls for cooling the outside unit comes on but the blower on the inside is not coming on and then the lines and everything starts to freeze up. The led status code shows continuous off. Any help would be greatly appreciated. Thanks

[@philfalz01]

thanks for the video

[@acservicetechchannel]

Thanks Phil!

[@Hewberman]

amazing

[@thrill2real]

When you say capacitor are you referring to the capacitor on the inducer motor?

[@tranceaddiction]

great work

[@acservicetechchannel]

Thanks PrimeMechCo!

[@137bob3d]

from your furnace controller PCB studies do you happen to know which of the PORTA,B or C pins of the 28-pin Microchip uC are in use. does Carrrier stick to just one port ? or are the signal pins scattered among the 3 ports ? and is this a variable model to model ? my repair approach is a dual one , first to follow your guidelines for checking accessory function & voltages and then to ID the uC pins involved , then monitor them w/ my 4-ch' digital scope during furnace operation. among other things this lets me quickly see if the ULN2003 chip is getting an 'on' signal for the relays. my furnace is 58DLA070-12 , mfg sept 2004. and is flaming out soon after ignition.

[@acservicetechchannel]

Hey Bob, you are very detailed in your approach to the microchips. I do not follow along with that aspect that much to be honest. I usually will replace the control board with a new one so as to avoid any warranty issues and because I don't have each component readily accessible for repair compared to being able to purchase the new board when needed at the local supply houses. Usually it is a relay that goes bad when they do fail. Not always but more times than not. Have you seen my flame rectification videos or pressure switch videos? You may want to look up those playlists as well for the circumstance you are mentioning, thanks! I also have links to playlists under the videos tab at acservicetech.com thanks!

[@hugoramirez196]

Thank you this is a very good vedio

[@acservicetechchannel]

Thanks Hugo Ramirez!

[@briang2566]

Question...wondering if you can provide direction, this morning my downstairs AC unit wasn’t blowing cold, I went out and checked to see if it was on and fan was working..it was, I then swapped thermostats and fan kicked on but still wasn’t blowing cold. I swapped the thermostats back...then the downstairs thermostat wouldn’t power on - checked the breaker, it was on - I reset it anyway. I then checked for 24v at the thermostat and nothing, went up to the furnace and checked the LED status light...it was off, code said to check for 24v power, SEC1 and SEC2, L1 & L2 - , after watching videos I checked for 24v at the transformer... (SEC1/2) nothing, 0 - I then checked for 110 by disconnecting the transformer and testing on the control board where it connected - PR1 & Neutral I believe, no power. I did ensure the power switch was on and the door switch pressed in - does this sound like a failed control board at this point? Thanks in advance for any direction you can provide...

[@briang2566]

The fuse is good - I checked it and it looked good, to be sure I swapped it with my upstairs AC since I didn’t have a replacement on hand and it works fine.

[@chupalia]

great video

[@acservicetechchannel]

Thanks chupalia!

[@mattfisher401]

Isn't the hot surface ignitor easy to see that's working?

[@bonafide6464]

I have an old Lennox 80UHG4/5-100a-3, igniter glows hot but gas valve did not kick on. I have a yellow and blue wire coming from the gas valve to the wire harness on the board. I measured voltage coming in to the gas valve from the board and it was only reading 12v. There is a transformer above the board with a yellow and blue wire that also connects to the same wire harness. I got 24v coming from the transformer to the harness. I pressed on the blue and yellow wires at the harness and wow! The gas valve turned on and fired up. I thought it was just a bad connection. Furnace worked fine overnight and was cycling on and off with temp set at 71. But this morning it’s not working again, same issue. What do you think it is?

[@acservicetechchannel]

Yes, you should do as you just did, measure for 24 volts at the gas valve and work your way back to see where it stops, possibly at that bad connection, thanks!

[@Ryan-ok2xr]

thank you! I have the same board except its number is 1012940JHK42FZ009. I will do this troubleshooting but if I have to replace the board, where can I buy one? The AC tech was less of a tech and more a salesman trying to get me to replace both my whole systems. He also quoted me $1500-$1800 for each pcb.... just to buy, not even install cost

[@johndoe-wt4ui]

I need a lot more practice to understanding this

[@acservicetechchannel]

Did you look up "acservicetech sequence of operation"? thanks

[@spike6095]

Good info, Thank You

[@acservicetechchannel]

Thanks John!

[@clarksafg]

If you ever work on nordyne units, it's probably the board+pressure switchs..lol

[@michaelkranz2529]

Control boards have a high failure rate , I change lots of them , it's usually a cracked solder joint at the back side of the molex connector,

[@acservicetechchannel]

Thanks Michael!

[@jonathanraul4086]

How do i test 4 a ground and if I have 2 bring a ground how do I do that I am a newbee and I love your videos ty i learned a lot of of u

[@acservicetechchannel]

Check this video out for troubleshooting ground problems on furnaces for flame rectification- kzbin.info/www/bejne/gqXJmJuLjsufY5Y - You would use the same gauge wire as stated on the max fuse or max breaker rating on the unit. 14 gauge is 15 amp, 12 gauge is 20 amp, thanks Jonathon!

[@samuelhall4056]

I have a goodman gmpn060-3 rev a furnace that is flashing the trouble code for reverse polarity and the blower will not shut off unless you flip the breaker to the furnace. Would this be a board problem?

[@acservicetechchannel]

That means that your 120v hot is accidentally on common and the common on the hot on the board. You can verify this with a multimeter on voltage or with the wiring diagram, thanks

[@Turtlesixfour]

I have a Rheem Criterion ii furnace. I was told that my HSI was bad so I replaced it with a new one that ohmed to 64 ohms. Checked voltage to the ignitor, but am not getting 120 v. More like 4 v. Any suggestions on what could be wrong? Thanks for your help in advance.

[@acservicetechchannel]

It sounds like you are having a problem with your pressure switch which needs to close before the board will power the hsi. It may not be the pressure switch but a clog in the condensate or clog in the exhaust or intake combustion pipes, thanks

[@cchavez302]

So one more question I replaced the board and my hsi is still staying on after its run it runs normal just the hsi is always on . So after the pilot lights what tell the hsi to turn off

[@nelsonc1687]

Hi what about if the board receives the DC microamps going back but is still saying that is not detecting flame could that be a bad board itself? Thank you really enjoy your videos like you say jajaja, thank you!

[@acservicetechchannel]

Could be but how high is the signal and is the board ground wire tight on the ground metal?

[@tamez082377]

Enjoyed the video but have a question about an issue that has been bugging me. The indoor fan blower is not working. I have 120 coming in to the board. I have 24 volts on r, g, and y so it's calling for cooling. Now on the relay I have 120 coming in but coming out of the relay going to the fan motor I have 94 volts. Has that relay gone bad or is there something else I'm missing? I haven't tested the fan motor directly yet so don't know if it even works. Appreciate any response you have. Thank you.

[@acservicetechchannel]

If you have a good common that you are measuring off of and the 120v is in and lower voltage is coming out with a low voltage call, tap the relay and continue to measure. If it jumps around or comes up to 120v the relay contacts on the board are bad, thanks

[@fedboy601]

pedro tamez call a tech