HVAC

Have HVAC Questions? Ask an HVAC Expert for Answers

Ask an Expert,
Get an Answer ASAP!

HVAC

My Furnace Is Running Constantly. Please Help!

Customer Question
My furnace is constantly running...

My furnace is constantly running. I changed the thermostat, but no change. The setting is on heat, and auto fan, but the fan is always on. It heats, and rest of the time circulates the air. It did not do this till 2 weeks ago, we brought a salesman to give us estimate on a new furnace. The only thing I can do is to unplug the furnace to turn off the fan. Please help.

Submitted: 8 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 8 hours by:
12/7/2009
HVAC Technician: Matthew, HVAC Technician replied 8 years ago
Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2,014
Experience: 14 years experience in the HVAC field of service, installation, Manual J & D calculations
Verified

When you have a moment go to the furnace control board where the thermostat wires hook up and take the wire that hooks to the G terminal off and see what happens. If the blower cuts off go to the thermostat with the wire still unhooked and test the system in heat and cool and see if it works the way it should.

Ask Your Own HVAC Question
Customer reply replied 8 years ago

The wires are connected to W, and R at the far right. What should I do now?

HVAC Technician: Matthew, HVAC Technician replied 8 years ago
You have heat only system then. Is this a gas or electric system? If you could find a model number that would be very helpful.
Ask Your Own HVAC Question
Customer reply replied 8 years ago

Yes it is heat only unit, and I disconnected W, from thermostat and nothing changed. This is a gas unit and model number from inside of the unit is 396GAW000075.

HVAC Technician: Matthew, HVAC Technician replied 8 years ago

That is a serial number I believe not a model number. The model number should start with letters. When the thermostat calls for heat, will the burners come on? And then when the temp is satisfied the burners go off and the fan just runs or do the burners never come on, is it just the fan?

Ask Your Own HVAC Question
Customer reply replied 8 years ago

The number that I gave you is the model number, there is a product number that is the same as the one I gave you plus ACAA. The serial number is very different.

The heat works fine, but after the shuts off, the fan does not stop, and I feel it is circulating the air.

HVAC Technician: Matthew, HVAC Technician replied 8 years ago

Your heat relay which is located on the printed circuit board is malfunctioning, if the heat works when it should, but the blower never cuts off. If the heat never worked and the blower just runs constantly then it would be the fusible link main limit. The only way to repair this is to replace the circuit board.

Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2,014
Experience: 14 years experience in the HVAC field of service, installation, Manual J & D calculations
Verified
Matthew and 87 other HVAC Specialists are ready to help you
Ask your own question now
Ask Matthew Your Own Question
Matthew
Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2,014
2,014 Satisfied Customers
Experience: 14 years experience in the HVAC field of service, installation, Manual J & D calculations

Matthew 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
No lights on control board, there is power, fan runs and
no lights on control board, there is power, fan runs and checked and replaced 3 amp fuse, (believe it was bad ) on control board, Nordyne kg6rc-080c-16b … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
My friend has a Amstar furnace that was installed about
Hi- My friend has a Amstar furnace that was installed about three months ago. Two weeks ago the 120/24V transformer and the fuse on the mother board blew. The replacement transformer lasted about ten … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
Both of my TH8321WF1001 Honeywell thermostats have gone
Both of my TH8321WF1001 Honeywell thermostats have gone dark? Seems like no power is going to it but I checked circuits and none are tripped.… read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
Have an t8411r thermostat. After several failed attempts to
have an t8411r thermostat. After several failed attempts to change temp. I turned off circuit breaker ---now screen is blank … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I wanted to replace a T8112D Thermostat with an RTH 111B and
I wanted to replace a T8112D Thermostat with an RTH 111B and in removing the T8112D, I accidentally touched the red and white wires. The system went on. I relaced the thermostat and the Air Cond came … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I have a honeywell chromorjem 111 but all it says is hold.
I have a honeywell chromorjem 111 but all it says is hold … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
I am having heating issues with what I believe is my
Hi Pearl... my name is ***** ***** I am having heating issues with what I believe is my thermostat … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I have a Lennox G40uh(X) series gas furnace that will not
I have a Lennox G40uh(X) series gas furnace that will not stop heating after it has reached the set temperature at the thermostat. Thermostat was replaced and problem continues. It does not do it ever… read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
How can I tell I my York furnace control board is the cause
How can I tell I my York furnace control board is the cause of the furnace not completing the heat cycle. It shuts down and give me the pressure sensor/switch code but two tech's have been out and ver… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Ruud Silhouette blower fan runs without end. Burners will
Ruud Silhouette blower fan runs without end. Burners will fire, fan stays on forever. … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
This is the same guy with the Goodman furnace control board
Hi, this is the same guy with the Goodman furnace control board / transformer. My plumber said what caused the board to fail was a short in the blower motor from water from AC unit backing up into blo… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
I have a Goodman GMNTE120-5 It has a furnace/control board
I have a Goodman GMNTE120-5 It has a furnace/control board with this part number B1809925two of the wires have come off two connectors, and the wires are the same color - trying to determine if it mat… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
I recently replaced my furnace control board. The furnace is
I recently replaced my furnace control board. The furnace is a Lennox G40-OUH and the control board was a White Rodgers 50-A65-121-07. The only replacement was a White Rodgers 50A65-843 Universal Boar… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
I have an amana furnace control board with an led flashing 3
I have an amana furnace control board with an led flashing 3 times … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I need help with my -Rodgers furnace control board 50e47-060
I need help with my White-Rodgers furnace control board 50e47-060 on a Trane furnace. It has a blinking red light. On the unit it says " steady red light- replace control, blinking red light-referred … read more
type2technician
type2technician
253 satisfied customers
I have a nordyne KG7TC-080D, with a furnace control board
I have a nordyne KG7TC-080D, with a furnace control board #624790/920916. this is a 2-stage upflow unit. Furnace ignites but goes out wihin seconds. flame sensor replaced, still the same issue. Has in… read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I think that I may have a bad furnace control board. Trouble
Hello I think that I may have a bad furnace control board. Trouble shooting so far. Two different thermostats with the same behavior. Direct connection of the R&W&G wires make the furnace run continuo… read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
My furnace control board light is not coming on. Yes, the
My furnace control board light is not coming on. JA: Did you check the furnace's filters? Customer: Yes, the furnace filter is new. JA: Do you plan on doing the work yourself? Customer: Yes. JA: Anyth… read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 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