How JustAnswer Works:

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

Ask Douglas Your Own Question

Douglas
Douglas, HVAC Technician
Category: HVAC
Satisfied Customers: 2927
Experience:  Manufacture Rep for Major Brand, Technical Trainer, NATE
27672032
Type Your HVAC Question Here...
Douglas is online now
A new question is answered every 9 seconds

My heat pump had ice build up on the outside coil, in heating

Resolved Question:

My heat pump had ice build up on the outside coil, in heating mode. The filter was probably the problem. changed filter, restarted the unit but the outside fan was not running. Should I just let the unit run, is there some time out feature before the outside fan starts up? I also know low freon, leaks, etc can cause iceing but am not equiped to take pressure readings. Don't want to call a service company if all I need do is let the unit go through a cycle. Also don't want to damage the unit. 20 yr old Trane WCXO30-SF-1A Has been working fine up to filter becoming clogged by my neglect.
Submitted: 4 years ago.
Category: HVAC
Expert:  Douglas replied 4 years ago.
For the most part, a dirty filter can cause problems but not generally a defrost issue. Defrost is controlled by a defrost control in the outdoor unit. This control of course is just a switch of sorts putting the unit into defrost mode. If the coil sensor is loose or has failed it may not go into defrost. The charge comes into play which produces inconsistant icing and ultimately does the work to defrost the coil so it can be refrigeration related to also.

in the outdoor unit, there should be a set of test pins to shift the unit into defrost mode while it's running.
Customer: replied 4 years ago.

Is the out side fan supposed to be running? Both coils are located outside in the unit. The outter most coil would be the evaporator in heat mode with the innermost coil actting as the condenser. Or I may be all wrong and the outter coil hasnothing to do with heat mode.

 

I just need to know if I should turn the system back on if the outter fan is not running.

Expert:  Douglas replied 4 years ago.
in defrost, no the fan should be off, but in normal heat pump mode, yes the outdoor fan should run. If it's not, that may explain the heavy ice.

The entire outdoor coil is the evaporator and your indoor coil is the condenser in heat mode. If the outdoor fan were not running in heat mode, the outdoor coil will drop in temperature quickly and form ice.

You may have either a bad outdoor fan relay, fan capacitor or just a bad fan.
Douglas, HVAC Technician
Category: HVAC
Satisfied Customers: 2927
Experience: Manufacture Rep for Major Brand, Technical Trainer, NATE
Douglas and 2 other HVAC Specialists are ready to help you
Customer: replied 4 years ago.

For defrost mode requires three conditions to be met.

heat mode

deforst termiant switch closed

compressor run time 50-90 minutes

 

So if I just started the unit the last condition could not be met and defrost mode is not what it is in. If so then fan is supposed to be running , it isn't, and of course would explain ice. Correct?

 

I need to have a service person check my fan, correct?

and thank you you have been helpful and of course I am going to accept. I use this service last night and a VET donated her time. I do not expect you to and will gladly reemburse.

Expert:  Douglas replied 4 years ago.
Just to be clear the run time accumulates. So say the unit runs for 30 minutes and satisfies the thermostat. When it restarts the time starts from 30 and eventually hit's the time period so if it ran say 45 minutes last cycle, it may only need to run 5 on the next cycle.

On the defrost control is a fan relay that opens when the unit is in defrost but should be closed otherwise (normal heating or cooling mode). They usually dont fail open but anything is possible.

I would at this point have it checked.... too much to go wrong on a few guesses.
Customer: replied 4 years ago.

Sorry about the delay I lost my connection. So now the question is am I in defrost mode and having disconnected power the unit would not start up in that mode would it.

 

It seems it the fan and I need to get a service guy out here. if you agree we will finish here and I can get on the phone,.

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. Jimmy Bagley, IA
< Last | Next >
  • 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. Jimmy Bagley, 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!!!! Alex Los 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. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, 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. Esther Woodstock, 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. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
< Last | Next >
  • http://ww2.justanswer.com/uploads/SE/ServiceTechRus/2012-6-7_2119_056.64x64.JPG gotoman for ac's Avatar

    gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
  • http://ww2.justanswer.com/uploads/AL/alumalite/2012-5-10_234018_shutterstock506249951forJA500.64x64.jpg Phil's Avatar

    Phil

    Mechanical Engineer

    Satisfied Customers:

    3888
    Retired HVAC/ Electrical & Boiler contractor. Industrial
  • http://ww2.justanswer.com/uploads/skibum0101/2008-12-16_015819_just_answer.jpg Rick Mather's Avatar

    Rick Mather

    HVAC Technician

    Satisfied Customers:

    3132
    35 years experience, HVAC
  • http://ww2.justanswer.com/uploads/RY/Rygis20/2011-5-7_3143_DSC5324.64x64.JPG Matthew's Avatar

    Matthew

    HVAC Technician

    Satisfied Customers:

    1994
    14 years experience in the HVAC field of service, installation, Manual J & D calculations
  • http://ww2.justanswer.com/uploads/KE/kentguidry/2011-9-26_214316_0059.64x64.jpg Kenton Guidry's Avatar

    Kenton Guidry

    HVAC Technician

    Satisfied Customers:

    962
    12 years install/service experience.
  • http://ww2.justanswer.com/uploads/solarman1947/2009-12-13_223915_phpkKBcXq_c2PM.jpg Rick Ridley's Avatar

    Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    871
    Retired But have had 30 years on the tools, Ex CORGI
  • http://ww2.justanswer.com/uploads/Ironheadfan/2009-12-18_222416_pump_005.jpg Tom's Avatar

    Tom

    HVAC Technician

    Satisfied Customers:

    770
    16+yrs HVAC/R service. Residential Commerical Industrial