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  1. #1
    Join Date
    Dec 2007
    Posts
    1

    Default A/Cunit freezes up

    I have a 2-story home in central texas (very humid) and my HVAC will not cool my home, 2400 sqft and the ac (coils not sure what it's called) will freeze up and then no air from the fan can get through to the plenum, I am completely at a loss. any help will be great,
    thanks

  2. #2
    Join Date
    Dec 2007
    Location
    Wichita,KS
    Posts
    6

    Default Re: A/Cunit freezes up

    Quote Originally Posted by harris8968 View Post
    I have a 2-story home in central texas (very humid) and my HVAC will not cool my home, 2400 sqft and the ac (coils not sure what it's called) will freeze up and then no air from the fan can get through to the plenum, I am completely at a loss. any help will be great,
    thanks
    It is the evaporator coil. The refrigerant absorbs heat from the air and cools the coil, which then returns to the condenser and compressor.

    There should be a water/condensation drain to allow condensation to drain. Also, coil is probably very dirty, holding water in the mud and blocking the air flow. The expansion valve, which controls the liquid refrigerant as it enters the coil is what keeps the temperature from going below freezing in the plenum.

    I would say, you have over charged the system, have not cleaned it properly and it is getting too little air flow because some of the distribution lines are blockwd or closed off.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: A/Cunit freezes up

    Question ... is this a heat pump or a central air unit ?
    Is this the coil inside the air handler that's freezing up?

    Is the fan ( blower ) for the air handler working ?

  4. #4
    Join Date
    Apr 2008
    Posts
    2

    Default Re: A/Cunit freezes up

    Have the unit checked for correct charge,its low on gas. When it is low on gas the refridgerant boils at a much lower temp. and moisture freezes instead of condensing into water and out the drain. It sounds like its just low on gas.

  5. #5
    Join Date
    Mar 2008
    Location
    Holliston, MA
    Posts
    19

    Default Re: A/Cunit freezes up

    I concur with hvacguy. Your gas level is low for I have the exact issue with my window unit whereby every year I need to add a little more gas to keep the coils from freezing. Unfortunately, I have not been able to find the leak in my unit yet.

  6. #6

    Default Re: A/Cunit freezes up

    Schrader ports are known for leaking -some caps have orings that fall out when serviced the brass caps are better. look for oil around the pipe work and coils.

  7. #7
    Join Date
    May 2008
    Location
    Derby City
    Posts
    42

    Default Re: A/Cunit freezes up

    It's scary to see so many individuals making a 'diagnosis' sight unseen. Yes, we can speculate on what the most common causes are for your particular situation; however, you should have a professional come out and go through your system. It could be anything from an improper refrigerant charge, to a leak, to a dirty coil, to a dirty filter, to a blower motor issue, etc.

    Get references from neighbors, friends, family, church members, co-workers, and then check the local BBB office. Find out what their service call covers, and what their labor warranty is.

    All the best, Irishmist

  8. #8
    Join Date
    Jan 2008
    Location
    Western Ky
    Posts
    21

    Default Re: A/Cunit freezes up

    Ours has done this many times. My husband is in the HVAC business. It's always low on gas and the coil needs to be cleaned. I would just have someone come and do service on it. You should do this at least once a year anyways.

    My husband always says if you have an upstairs then you need a seperate unit for it if it's going to work properly.

  9. #9
    Join Date
    May 2008
    Location
    Derby City
    Posts
    42

    Default Re: A/Cunit freezes up

    morcolt: Just up the road from you. I am sure you would agree that if this is a re-curring problem, i.e. "ours has done this many times," that it may very well be an indication of another, possible bigger problem.

    If you consistently have to add refrigerant to the "sealed circuit" then chances are you have a leak somewhere in the system. This could be at the indoor coil, the outdoor coil, or anywhere else in that refrigeration circuit.

    To your second point, a second unit for the upstairs is not the "end all - cure all" solution. With very good zoning controls available today, it is not necessary to install two separate systems. With a properly designed and installed zoning system, a single system can provide independent heating and cooling to two or more spaces.

    All the best, Irishmist

  10. #10
    Join Date
    May 2008
    Posts
    13

    Default Re: A/Cunit freezes up

    Please call a Licensed Contractor. As an HVAC contractor in the business for nearly two decades, I will tell you over-charged systems are VERY common, its the knee-jerk solution to dump more refrigerant in the system, many times leading to compressor failure, and severe in-efficiency.
    There can be many causes for freezing, from improper air flow, to metering device problems, relay/circut board issues, motor protector tripping, and yes low refrigerant charge......which means you need to have a leak search done (unless this was a brand new install, never properly charged). With R-22 at nearly $10.00 a lb wholesale, just adding 'gas' is not really in your best interest.
    Have you changed your filter lately? This actually one of the most common cause of freezing......dirty filters, in my experience.
    Last edited by KellyWayne; 05-26-2008 at 01:38 PM.

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