Ugh, AC unit has frost/ice build up. What's causing this?

Discussion in 'HVAC Heating & Cooling' started by ironspider, Jun 23, 2009.

  1. ironspider

    ironspider Member

    Messages:
    68
    Location:
    Michigan
    Greetings all,

    We recently turned back on the Central AC Unit and we noticed that it isn't blowing very cool through the vents and then, after a while, it isn't blowing cold air pretty much at all :(

    So we went outside to look at the unit and we noticed that the connector is iced up!

    I've attached an image below--does this look like some kind of common culprit? And, if so, what needs to be done to fix it and about how much is that going to run us?

    Thanks in advnace for any help you can give us!

    Attached Files:

  2. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    You likely have a leak in your refrigerant or you were running the system on a super cool night.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    This is generally not DIY. There are a million things...some real bad, some not so bad.

    Could be as simple as a clogged filter drier, dirty evap and/or condenser coils, needs a charge, etc.

    Time to get a well qualified HVAC tech to take a look. He will get his gauges on the high and low sides, calculate the super heat, check the delta T across the drier, evaluate the coils and clean as necessary, etc.
  4. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    It's probably low on freon and needs cleaning.

    The quickest way to get some cool air is to set the fan to continuous and then set the thermostat up until the unit cycles on and off.

    This will give you a little bit of cool air, however it won't be as efficient.
  5. GTzephyr

    GTzephyr New Member

    Messages:
    1
    Location:
    minnesota
    any actual resolution on this?
  6. gator37

    gator37 Retired prof. engr.

    Messages:
    108
    Location:
    Alabama
    The first thing you will have to do is let the evaporator (inside unit) thaw out which will take a little while for the ice to melt.
    Check for a clogged filter.
    Check for a dirty coil especially if you have ever run your unit with out a filter. You will have to clean the coil
    Check to see if you blower (evaporator) fan is operating....blowing air
    See if you can see where the ice stops it the coil is not icing up. Where it stops is probably the bad component....expansion valve if you have one...or filter dryer...etc.
    If none of the above you may have a leak as mentioned previously of which you will have to get a mechanic to check the pressures and find the leak.

    Whoops if you have a heat pump it may be another problem such as an expansion valve
    Last edited: May 28, 2010
  7. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    Short of cleaning the evap and condensor coils there is nothing more a homeowner can do. It can be caused by any one of many factors and even a combination of several. Call an HVAC tech.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    If it is low on Freon, then it is not a DIY job to locate the problem or repair it.
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    As opposed to an automobile a/c system which has various hoses which can (very) slowly leak refrigerant, a home a/c unit has all soild metal connection. The only place a home a/c unit can leak is through seals. An auto system will lose refrigerant. It gets very messy legally about just putting refrigerant into a system that is leaking. Dumping refrigerant into the atmosphere is not good for the environment, and fixing it right is what is needed.
  10. centralairunits

    centralairunits New Member

    Messages:
    3
    Location:
    Japan
    That's right
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