HVAC

Have HVAC Questions? Ask an HVAC Expert for Answers

Ask an Expert,
Get an Answer ASAP!

HVAC

My 5 amp fuse keeps blowing. the low voltage wires are clear

Customer Question
my 5 amp fuse keeps...
my 5 amp fuse keeps blowing. the low voltage wires are clear of shorts, so I don't know what to do next and it's 15 degrees
Submitted: 6 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 3 minutes by:
2/3/2011
HVAC Technician: Matthew, HVAC Technician replied 6 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
Matthew :

Hello, My name is ***** ***** I will do my best to help you today.

Matthew :

Check at the outdoor unit. You have to eliminate one part of the equation at a time. At the furnace take the wires off that come from the outdoor unit see it blows. If it doesn't then the problem is a wire to the outdoor unit or a part in the outdoor unit. Put the wires back and then go to the outdoor unit and unhook the wires there. If it doesn't blow then the problem is a 24v part in the outdoor unit. It it blows then the problem is in the wires to the outdoor unit. Same thing with the thermostat.

Matthew :

If you unhook all wires from the furnace and put a jumper from R to W and the fuse blows then the problem is internal to the furnace control board or transformer.

JACUSTOMER-rjbsr9fv- :

i skipped to the jumper part to test the board first and it has been running for 10 minutes without tripping. Do you think it is determinable to eliminate this portion and move on to the next test?

Matthew :

you took the wires off from the thermostat and the outdoor unit and just put a jumper from R to W on the control board?

Matthew :

meaning you took the wires off at the furnace

JACUSTOMER-rjbsr9fv- :

yes

JACUSTOMER-rjbsr9fv- :

i went ahead and replaced the thermostat wires now and i'm testing the termostat with the furnace now. When I turn the "heat" mode on the thermostat, the furnace won't run. The furnace will turn on when I put the thermostat on the "fan" mode though.

Matthew :

Is this a gas furnace?

JACUSTOMER-rjbsr9fv- :

no

Matthew :

Heat pump then with an electric back up furnace?

Matthew :

jumping R and W at the control board of an electric furnace is only going to energize the electric strips and the furnace not the outdoor unit. So it could still be that the outdoor unit is causing the direct short. It is a bit more complicated to track down with a heat pump and electric furnace then it is with a gas furnace and conventional outdoor unit.

Matthew :

Another thing with an electric furnace is that when you jump R and W you are running the blower call through the heat sequencer. When the thermostat calls for regular heat it energizes the outdoor heat pump and the furnace blower but the blower is energized through the blower relay in this case. So you see it could be this blower relay, it could be the outdoor unit, it could be the thermostat, it could be the wires. You have to unhook and hook wires one at a time at the furnace until you see which causes the fuse to blow.

Ask Your Own HVAC Question
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

6,730 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
My furnace blower wiil not start. Hopefully. Furnace tries
my furnace blower wiil not start JA: Did you check the furnace's filters? Customer: no JA: Do you plan on doing the work yourself? Customer: hopefully JA: Anything else we should know to help you best… 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
My evcon furnace blower fan cycles every day at 8:20 with no
My coleman evcon furnace blower fan cycles every day at 8:20 with no demand and no exhaust fan operation. It just co es on runs for 2 minutes then shuts down, and there was no previous heat dema d … read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
My Nordyne furnace blower starts immediately when I turn on
My Nordyne furnace blower starts immediately when I turn on the switch. The LED light on the control board flashes 5 times. There is no flame. … read more
Regan Land
Regan Land
General Manager
Vocational, Technical or Trade Scho
508 satisfied customers
My '92 Carrier model 58ssc furnace blower motor has finally
Hi! My '92 Carrier model 58ssc furnace blower motor has finally quit. I wonder what I can replace it with … 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
We have a question about a furnace blower that is not
We have a question about a Bryant furnace blower that is not working. The model number is ***** We have noticed a blinking light error that has two short and four long blinks. … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I have a loud noise coming from furnace blower motor. Do i
I have a loud noise coming from furnace blower motor. Do i need to oil up the motor? Its a lennox g40uh (x) … read more
Rick the plumber
Rick the plumber
Owner
9,857 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'm replacing a furnace blower motor and assumed it would be
I'm replacing a furnace blower motor and assumed it would be plug and play. Old motor had 5 wires; white, brown, black, red and blue. The brown and white went to the cap, with another white wire comin… read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
343 satisfied customers
My furnace blower won't shut off. Have confirmed it's not
My furnace blower won't shut off. Have confirmed it's not the thermostat (by disconnecting same). Could the fan relay cause this? … read more
derekh1966
derekh1966
0 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
My furnace blower will turn on but the AC condenser wont. I
My furnace blower will turn on but the AC condenser wont … read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,730 satisfied customers
Furnace blower cycle on and off even when thermostat is in
furnace blower cycle on and off even when thermostat is in the off position. … read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 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
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