HVAC

Have HVAC Questions? Ask an HVAC Expert for Answers

Ask an Expert,
Get an Answer ASAP!

HVAC

Lennox G20 Furnace Not Firing Up After Temperature Falls

Customer Question
I have a Lennox Whisper...
I have a Lennox Whisper Heat G20 furnace and had been having problems with it not firing up every time the thermostat went below the desired temperature. I'd have to turn the furnace off/on to get it to fire up again. Then, after asking a tech here, they suggested I first try and clean the flame sensor with steel wool. Unfortunately, after doing so, the unit would fire up, but then turn off almost immediately, leaving no heat at all.
Today, I replaced the old RobertShaw ignition control module with a Honeywell 30W33 updated one. After I'd turn the gas back on and turn the power back on, it would lite the pilot, then fire up with no problem. The PROBLEM, however, is that it won't fire up again when the temperature falls below the desired temp at the thermostat. I have to turn off the furnace, and the gas as well if I'm going to start it again. Could this new module be faulty? The man at the parts store made it clear that they don't take back equipment unless it's faulty.
Submitted: 7 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 9 minutes by:
1/30/2010
HVAC Technician: ComfortZone, HVAC Technician replied 7 years ago
ComfortZone
ComfortZone, HVAC Technician
Category: HVAC
Satisfied Customers: 516
Experience: 10 years in the HVAC industry.
Verified

Perhaps it is the control board or the stat that is faulty.

Do you have a volt meter?

Ask Your Own HVAC Question
Customer reply replied 7 years ago

Actually, I do...but must admit, I'm not that comfortable in how to use it. It's a "50/60HZ Voltage tester GVT-82".

As for the thermostat, it's brand new since that was the very first thing I'd tried to change when the furnace started going cold (sorry I forgot to mention that).

HVAC Technician: ComfortZone, HVAC Technician replied 7 years ago

When the furnace does not start does the LED on the control board flash at all?

Ask Your Own HVAC Question
Customer reply replied 7 years ago
Yes, first the green light blinks six times and the yellow one, once...the second time the green blinks four times and the yellow, three...then it repeats.
Customer reply replied 7 years ago

I'm sorry, are you talking about the circuit board that is just above the blower motor (behind the bottom panel) or are you talking about the two LED lights on the Honeywell Ignition control module?

HVAC Technician: ComfortZone, HVAC Technician replied 7 years ago

The one above the motor where all the thermostat wires are attached.

Ask Your Own HVAC Question
Customer reply replied 7 years ago
just went down to check and didn't notice any lights at all on the circuit board in the blower compartment as I tried to start the furnace.
HVAC Technician: ComfortZone, HVAC Technician replied 7 years ago
I am not sure what your problem is, but I suspect it is the control board. Without voltage readings I would not condemn the board though. Since I am not a Lennox expert I will opt out and give another expert a shot at this.
Ask Your Own HVAC Question
Customer reply replied 7 years ago
thank you for trying.
HVAC Technician: gotoman for ac, HVAC Technician replied 7 years ago
gotoman for ac
gotoman for ac, HVAC Technician
Category: HVAC
Satisfied Customers: 5,288
Experience: 51 years of experience install design and repair of all makes and models of AC
Verified

I am an old Lennox Engineer. Most of the time on these Whisperheat units it is the igniter. Everytime I change one it is a diffferent manufacturer. Does the furnace lite now? Tell me what it doing now. Also do you need an install manual with all the trouble shooting procedures. So you can follow.

Ask Your Own HVAC Question
Customer reply replied 7 years ago

Thanks for your reply, Rus. As of right now, the only time the furnace will light is when I turn the gas and power off, then put the gas back on again (at the regulator) and turn the power back on. The furnace will then light the pilot, seconds later you hear some clicks, and seconds later the burner ignites...but then that's it. It does not come on again by itself when the temperature falls below the desired setting on my thermostat.

I guess the reason I'm wondering if it could be a faulty new ignitor module is that when I went to buy it at the appliance parts store, the box was already open when the man brought it to the counter. Just seemed "odd", especially now because it does work initially, but like I said, only the one time.

As for the install manual, the Honeywell 30W33 did come with a 4 page installation booklet, but there are no troubleshooting methods in it.

HVAC Technician: gotoman for ac, HVAC Technician replied 7 years ago

go to www.cozyparts.com/Lennox-Parts/forum/Lennox/furnaces/G20_01_2003.pdf

for complete manual. This way we will be on same page. It is leaning toward igniter. Check trouble shooting chart in back of manual. Get back if you need help.

Ask Your Own HVAC Question
Ask gotoman for ac Your Own Question
gotoman for ac
gotoman for ac
gotoman for ac, HVAC Technician
Category: HVAC
Satisfied Customers: 5,288
5,288 Satisfied Customers
Experience: 51 years of experience install design and repair of all makes and models of AC

gotoman for ac 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

6,938 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
I changed the ignite on my heil NDGK. It's still not
I changed the ignite on my heil NDGK. It's still not heating … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I have a lennox zoned heat pump and it is not heating down
I have a lennox zoned heat pump and it is not heating down stairs. … read more
HvacmanSean
HvacmanSean
Owner
HVAC
229 satisfied customers
I have a new Beckett Genisys 7505 oil furnace that stopped
I have a new Beckett Genisys 7505 oil furnace that stopped working last night. I completely filled the oil tank and have reset the furnace a few times, but when I try to turn on the heat I get cold ai… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Aprilaire 700. Water is getting to the switch at the bottom
Aprilaire 700. Water is getting to the switch at the bottom of the unit but not proceeding up into the unit to the filter element. … read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,938 satisfied customers
We have a new HVAC gas pack. It is a Daikin DP16GM3008041,
We have a new HVAC gas pack. It is a Daikin DP16GM3008041, 2.5T PKG Gas, 16 SEER. The filter I am using is a Honeywell Elite Allergen 10 FPR. It makes a whistling sound when the unit runs and seems re… read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,938 satisfied customers
I am showing the e24 on my thermostat and our temp here is
I am showing the e24 on my thermostat and our temp here is going to be in single digits later tonight. I am a widow and have not idea about taking off panels on the furnace. Help … read more
gotoman for ac
gotoman for ac
HVAC Technician
5,288 satisfied customers
I have a rheem manufacturing company model # rkma-a060jl10e
I have a rheem manufacturing company model # rkma-a060jl10e it does not want to work. We found that the gas had been turned off to it so I turned it back on. Is there a pilot light or something that n… read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
I have XV95 and I just got a new Ecobee3. It says it's
I have XV95 and I just got a new Ecobee3. It says it's heating but I am fairly sure that only the fan is running … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I have water leaking from the furnace. Actually quite a bit!
I have water leaking from the furnace. Actually quite a bit! … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I turned on my built in fireplace for the first time
i turned on my built in fireplace for the first time yesterday. I came on for 1 minute and turn back off. I could here a click every time it would turn on and off. I was leaving the house after it tur… read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,938 satisfied customers
I have a lennox heat pump with12.5 eer i bought about 25
i have a lennox heat pump with12.5 eer i bought about 25 years ago. i live in south Texas and use heat every other year. the AC works good, last month it was cold. i turned on heat pump, worked overni… read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
How do you change the thermal high limit swtiches on a
How do you change the thermal high limit swtiches on a PTH123E35Axxab PTAC. Looks very difficult. … read more
gotoman for ac
gotoman for ac
HVAC Technician
5,288 satisfied customers
I have an Aprilaire steam humidifier Model 800. It is two
I have an Aprilaire steam humidifier Model 800. It is two years old and apparently has not been serviced at all. Recent cold weather drove the humidity down to the point where we had to call a technic… read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
We have a 10 year old Goodman cple 48 hvac heat pump Ac
we have a 10 year old Goodman cple 48 hvac heat pump Ac unit, breaking the tripper. My hubby wants me to find a NEW unit to replace entire system we are very very unhappy with this goodman kept capici… read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I have a keeprite furnace that has a constant yellow light
I have a keeprite furnace that has a constant yellow light flashing on the panel cover. I'm not sure if this is normal or there is an issue? … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
Rheem gas furnace RGRA10EZAJS that purges air then blows
Rheem gas furnace RGRA10EZAJS that purges air then blows cold air for a minute, stops, purges again, then flames and blows hot. Or sometimes after first purge does hiccup purges again then flames. Rep… read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
384 satisfied customers
Comfort glow Cumberland natural gas logs new, won't light
Comfort glow Cumberland natural gas logs new, won't light first time....gas works to the unit, pilot ignites but won't light any gas. Gas is not “heard” when on. Unit has been bled several times. Any … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
How do i turn of the high efficiency mode, it's a new
it's a new machine can't stand the high efficiency mode … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 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