HVAC

Have HVAC questions? Ask an HVAC Expert for answers

Ask an Expert,
Get an Answer ASAP!

My air handler was sometimes staying on after the unit outside…

Customer Question
My air handler was sometimes...
My air handler was sometimes staying on after the unit outside would shut off and sometimes it would not come on at all when the unit started up. I could turn the breaker off for a couple hours and it would come back on and run fine for a couple weeks and then do the same thing. Now the air handler won't come on at all. Trane XE1000 heat pump. air handler is under house. Service tech said he couldn't advise me unless he was actually there when it was acting up. Any thoughts?
Submitted: 2 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 29 minutes by:
5/30/2015
HVAC Technician: Phil, Mechanical Engineer replied 2 years ago
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6,938
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Verified
Welcome!
The technician was absolutely correct... and honest. Some technicians would have resorted to selling parts until the problem was resolved.
The problem is most likely in the thermostat, or the printed circuit card inside the air handler that the thermostat wires end up being attached to.
I have developed a heat stress test that works about 70% of the time on the printed circuit cards.
Use a hair drier to slowly and gently warm the card to 120F (warm to the touch but not hot and not over 140F)... if you get any change in behavior that means the card is bad...
A micro crack has opened in the printed circuit at a solder joint, or inside its CPU in that case .... or a short circuit has developed as the card expanded when you heated it.
Constant expansion and contraction as these electronics heat and during their duty cycles over the years is what wears these cards out.
It is also a good idea to replug all of the connections in the unit, that burnishes any oxidized terminal connections and will sometimes solve the problem, especially at the printed circuit card and in any sensor molex connectors. Do that with the power off to the unit of course.
These cards are also damaged by Electrical Spikes caused by power failures and lightning. These high voltage spikes can literally explode the fine 'wire' connections inside the chip. There is also a shunt type device, often printed on to the card that allows a high voltage spike to arc across to ground harmlessly, some of these can wear out after a few times and allow the high voltage spike into the rest of the card and the CPU micro-circuits. The high end printed circuit cards use a large capacitor like device, or several in parallel, to capture and release such surges, these do not wear out.
We can go from there.
.
Ask Your Own HVAC Question
Customer reply replied 2 years ago
Ok so if I replace the old thermostat with the new Honeywell T3210D how do I wire it?The old baystat has wires on the following terminals:R-red wire
T-black wire
o-orange wire
G-green wire
Y-Yellow wire
X2-blue wire
B-black wire
W-white wireThe terminals on the 3210 are as follows:E
Aux
Y
G
O
L
R
B
C
HVAC Technician: Phil, Mechanical Engineer replied 2 years ago
Hello again, replacing parts prior to diagnosis can end badly, especially prior to discussing it with the expert first... these thermostats especially mixing Honeywell and Trane parts can be complex and introduce new problems, so that you can end up with an unfathomable mess that can take hours to resolve, and of course that does not fit our ultra low price structure.
I will opt out, hopefully other of our experts here will want to get involved.
.
Ask Your Own HVAC Question
Customer reply replied 2 years ago
You stated the problem was most likely in the thermostat and then you come out with this? Wow. If the other "experts" are as good as you I think I will pass.
HVAC Technician: gotoman for ac, HVAC Technician replied 2 years ago
gotoman for ac
gotoman for ac, HVAC Technician
Category: HVAC
Satisfied Customers: 5,335
Experience: 51 years of experience install design and repair of all makes and models of AC
Verified
Russ here. Welcome. I am here to help. Please do not rate until you are satisfied with answer. Always available for follow up questions.
On that age Trane unit the problem is going to be the fan relay. The fan relay has piggyback time delay board on it. This board goes bad and gives the same systems you have noted. . You can remove the time delay really and just use fan relay. Russ Trane Dealer
Ask Your Own HVAC Question
Was this answer helpful?
Ask Phil Your Own Question
Phil
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6,938
6,938 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

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 have a interior wall mounted Lennox Mirage Magnum Inverter
I have a interior wall mounted Lennox Mirage Magnum Inverter 17 model # EMF181N ,when I use the hand control and press mode to turn on the Heat Mode I can not get any heat,I have tried all different T… read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
Why does my vacuum pump suck and then blow the cap off of
Why does my vacuum pump suck and then blow the cap off of oil side cap off of pump while trying to pull a vacuum … read more
hvacdave84
hvacdave84
53 satisfied customers
I think the water drain pipe for my AC is getting clogged
I think the water drain pipe for my AC is getting clogged (maybe due to algae growth or dirt), the water is dripping out on the pan underneath the unit and flowing out from another pipe connected to t… read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
How to design hard pipe duct work for 5 ton unit going
How to design hard pipe duct work for 5 ton unit going across the room(75ft)? … read more
hvacdave84
hvacdave84
53 satisfied customers
HIVAC turns on for only 2 min then shut down, then when
HIVAC turns on for only 2 min then shut down, then when restarts it starts and then shuts down stright away … read more
gotoman for ac
gotoman for ac
HVAC Technician
5,335 satisfied customers
Thanks for your update. It looks like I will need to have
Thanks for your update. It looks like I will need to have the inside acoil cleaned. What is the cost estimate to have the inside coil removed cleaned and reinstalled. Thanks… read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,800 satisfied customers
I need a Honeywell valve for a fireplace part number
I need a Honeywell valve for a fireplace part number VS8420E-2038, which is obsolete. Is there a current part that will work? … read more
hvacdave84
hvacdave84
53 satisfied customers
Coupe questions: 1) We have preventative maintenance
Coupe questions: 1) We have preventative maintenance contracts in place... We recently sent techs out to these sites and it was determined that they were 7lbs short of freon (almost empty I guess) but… read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I have a Vulcan gas central heater, I was changing the
I have a Vulcan gas central heater, I was changing the temperature I wanted on the wall controller, now that temperature is blank and I can not reset. … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,800 satisfied customers
This house is missing the circuit breaker for the disconnect
This house is missing the circuit breaker for the disconnect for the outside ac unit. What do I need to get to repair this?… read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I have a 4 wire thermostat and upgrading to a thermostat
I have a 4 wire thermostat and upgrading to a thermostat that requires a common wire. There is an additional wire but I don't think it's connected to the hvac system. I live in an apartment and the fu… read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
452 satisfied customers
My cental air is not working in my home. the unit outside is
my cental air is not working in my home. the unit outside is running , but no air is coming out of my vents … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
Have a csm code on my hayward prologic system what does that
have a csm code on my hayward prologic system what does that mean … read more
David Bowden
David Bowden
Owner
848 satisfied customers
My inside blower motor isn't working. I have 4 wires: yellow
my inside blower motor isn't working. I have 4 wires: yellow brown red and black. Show can I test to see if blower works … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Fb4cnf030, power drops to the thermostat and the unit stops
fb4cnf030, power drops to the thermostat and the unit stops running, but without doing anything it comes back for a while and then drops again … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
My AC isnt working and my thermostat is flashing P-. It is a
Hi, my AC isnt working and my thermostat is flashing P-. It is a carrier33CSSP2-FC … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I have a Lennox HS19-411u-79 air conditioner. It has started
I have a Lennox HS19-411u-79 air conditioner. It has started to drain water out of the overflow pipe along with the regular pipe that leads outside ( this part of the unit is enclosed) will drop for h… read more
Brian HVAC Guy
Brian HVAC Guy
HVAC Technician
High School
953 satisfied customers
Tried to turn on furnace after being off for a few days. air
tried to turn on furnace after being off for a few days. air conditioning was running and we had a cold spell. Blower kicks on, element heats up (78ohms tested) and flame ignites but shuts off after a… read more
Phil
Phil
Mechanical Engineer
6,938 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