HVAC

Have HVAC questions? Ask an HVAC Expert for answers

Ask an Expert,
Get an Answer ASAP!

I am changing a Lennox control board old part # 97L4801 to a…

Customer Question
I am changing a Lennox...
I am changing a Lennox control board old part # 97L4801 to a replacement board Emerson/white-Rodgers 21D83M-843.
The old board has 1 green wire and 1 yellow wire going to 24 VAC Return Pins and 1 blue going to a 24 VAC hot pin but the new board doesn't have these pins but has these color wires coming from one of the adapter wire harnesses. I see that I can plug the new yellow right to the XFMR and the blue to a circuit breaker that then continues to the XFMR but the green comes off the old board and splits going to a screw next to the transformer (looks like a ground) and the other half goes up into the furnace. The new green wire doesn't split and just has a connector that would fit onto a pin. How do I connect this?? Thanks
Submitted: 3 months ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 4 minutes by:
1/9/2018
HVAC Technician: Phil, Mechanical Engineer replied 3 months ago
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 9,310
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Verified

Hello. as the broad rule. you must replace the Lennox control boards with an *identical replacement... any time you use a board with different wire connections the odds of it working drop radically. Something like taking the printed circuit board from a very very nice toaster and trying to use it as the mother board in your PC....

.

Ask Your Own HVAC Question
Customer reply replied 3 months ago
They don't make the old one any more. This is the replacement that you get when you order the old part number
HVAC Technician: Phil, Mechanical Engineer replied 3 months ago

Hello again, it seems that *you understand the situation rather well, it is a bit hard to parse your narrative however into something that I can grasp as clearly on this end.

.

so we can discuss it a bit at least.

You understand that there are two poles on the 24volt transformer, and if you are sure the yellow and green shown connected in your first photo, go to one side of the transformer, and that the blue goes to the other side of the transformer, you can most likely connect that way...

.

if you try that, buy 2 each 2 amp automotive type fuse and fuse holder for it and wire it them series with the blue wire, and yellow wire connections ...that might save your new board if we are incorrect in our assumptions.

.

Let me know if this makes sense on your end or not... we can go from there.

.

Ask Your Own HVAC Question
HVAC Technician: Phil, Mechanical Engineer replied 3 months ago

Ooops, my edit needs fixing

if you try that, buy 2 each 2 amp automotive type fuses and fuse holders for it, and wire them in series with the blue wire, and yellow wire connections ...that might save your new board if we are incorrect in our assumptions.

Ask Your Own HVAC Question
Customer reply replied 3 months ago
Its actually yellow and blue which go to either side of the transformer. It looks like green is just a ground. Green and yellow were connected on the same pin then green went to a grounding screw and yellow went to transformer. Yellow and blue both fit on new board Its just the green ground that doesnt have a place to go
HVAC Technician: Phil, Mechanical Engineer replied 3 months ago

Go ahead and try it...

.

The 2 amp fuses however are too small to support the normal amperage draw of that board... but for test purposes, if they blow instantly we know for a fact that its wired wrong... if they take a few seconds or a minute to blow, then the wiring is likely correct and you can remove the fuses and fuse holders and rely on the 3 amp fuse that is most likely fit into the new board

Ask Your Own HVAC Question
HVAC Technician: Phil, Mechanical Engineer replied 3 months ago

If all that works

Its time to rate my input for the day, that gets me paid, locate the "finish and rate your expert" link near the top of the page and click on it. I will appreciate that very much.

I am in every day from 9 am to 11 pm west coast USA time to do any follow up needed.

Ask Your Own HVAC Question
Was this answer helpful?
Ask Phil Your Own Question
Phil
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 9,310
9,310 Satisfied Customers
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial

Phil is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Phil

Phil

Mechanical Engineer

9,310 satisfied customers

Retired HVAC/ Electrical & Boiler contractor. Industrial

Rick Mather

Rick Mather

HVAC Technician

3,133 satisfied customers

35 years experience, HVAC

Matthew

Matthew

HVAC Technician

2,014 satisfied customers

14 years experience in the HVAC field of service, installation, Manual J & D calculations

Kenton Guidry

Kenton Guidry

HVAC Technician

963 satisfied customers

12 years install/service experience.

Brian HVAC Guy

Brian HVAC Guy

HVAC Technician

953 satisfied customers

I have been an HVAC/R mechanic/technician for 30+ years.

Rick Ridley

Rick Ridley

UK Heating Engineer

871 satisfied customers

Retired But have had 30 years on the tools, Ex CORGI

Tom

Tom

HVAC Technician

770 satisfied customers

16+yrs HVAC/R service. Residential Commerical Industrial

< Previous | Next >

Related HVAC Questions
Our thermostat do not work efficient after reset cool. Do we
Our thermostat do not work efficient after reset cool. Do we need reset circuit breaker? How? … read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 satisfied customers
The compressor trips the circuit breaker in the house, not
the compressor trips the circuit breaker in the house, not immediately, about after 5 minutes. what are my options? can i replace only the compressor? It is a frigidare model FS3BC-042KA … read more
Chris Wagner
Chris Wagner
None
27 satisfied customers
Air Handler # NFCX3600C2 what causes the circuit breaker
Air Handler # NFCX3600C2 what causes the circuit breaker panel to fry? I replaced it once and the heat worked OK but when I tryed to run A C the board fryed again … read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
450 satisfied customers
I have a Trane Split System Heat Pump model #TWR030C100A2
I have a Trane Split System Heat Pump model #TWR030C100A2 that's stuck in defrost mode … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
Turned off circuit breaker while furnace running ... turned
turned off circuit breaker while furnace running ... turned on circuit breaker ... furnace did not come back on ... got message system malfunction outside sensor error on carrier infinity 96. read you… read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
450 satisfied customers
MY STOVE HAS C01 DISPLAYED I TURNED OFF CIRCUIT BREAKER AND
MY STOVE HAS C01 DISPLAYED I TURNED OFF CIRCUIT BREAKER AND IT RESET FOR A TIME THEN DISPLAY CAME BACK UP … read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
I have a Heil CA5536VKD2, circuit breaker trips when it
i have a Heil CA5536VKD2, circuit breaker trips when it turns on compressor runs for like a second then trips bad compressor? … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
I turned the circuit breaker off to my AC to replace a
I turned the circuit breaker off to my AC to replace a thermostat with a NEST thermostat. When finished, I turned the CB back on. No power. I put the old thermostat back on and still no power at therm… read more
Regan Land
Regan Land
General Manager
Vocational, Technical or Trade Scho
508 satisfied customers
Will a weak capacitor trip the circuit breaker. Today only
well I can tell you I took off a fan motor that had 3 wires and replaced it with one with 4 wires… read more
Phil
Phil
Mechanical Engineer
9,310 satisfied customers
I woke up this morning to a tripped furnace circuit breaker,
I woke up this morning to a tripped furnace circuit breaker, I reset it and went up to the furnace and also noticed a burning smell and a humming noise.… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
My HVAC is not working. The AC circuit breaker trips as soon
my HVAC is not working. The AC circuit breaker trips as soon as the, I guess, the outside unit try to start … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,514 satisfied customers
The circuit breaker keeps shutting off when the Rheem
The circuit breaker keeps shutting off when the Rheem furnance/air conditioner tries to come on. What is our problem? We just had a new capacitor put in about two weeks ago. … read more
D.E. Anderson
D.E. Anderson
Industrial Refrigeration Service Manager
200 satisfied customers
What size amp circuit breakers needed for lennox heat pump
what size amp circuit breakers needed for lennox heat pump 14hpx-036-230-21 and Lennox air handler cby25uh-036-230-10? … read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
8,099 satisfied customers
On my Model 213C A/C, I have: Reset the circuit breaker,
On my Bryant Model 213C A/C, I have: Reset the circuit breaker, Replaced the fuses, Replaced thermostat batteries, Replaced the capacitor, Replaced the circuit board. Our A/C unit is less than five ye… read more
Phil
Phil
Mechanical Engineer
9,310 satisfied customers
The circuit breaker that I plugged my window unit into
The circuit breaker that I plugged my window unit into wasn't labeled so it got too much voltage when I plugged it in and it seems to have blown an internal fuse. I'm trying to figure out which compon… read more
Phil
Phil
Mechanical Engineer
9,310 satisfied customers
Circuit breaker cutting off no ac or ac will not run,
circuit breaker cutting off no ac or ac will not run … read more
HvacmanSean
HvacmanSean
Owner
HVAC
232 satisfied customers
I turned off circuit breaker to cleanup a water problem in
Greetings, I turned off circuit breaker to cleanup a water problem in my house. As I went to turn on the heat it would start up but then turned back off. Please can you send me some pictures or a link… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
My thermastat is blank I have reset my circuit breakers
My thermastat is blank I have reset my circuit breakers although they were not tripped , taken it off wall and replaced , still no reading … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x