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  • AC unit frozen?

    So I have an older home, built in 1984. The AC unit is original. It seems to work fine but last night the house didn't cool that much. This morning when I woke up the unit inside (in the hall closet) was frozen. The coils on the top had ice on them. I shut the unit off. What else can I do, what do I do to fix this?

    Thank you.
    Gus
    M40607

  • #2
    Re: AC unit frozen?

    The only reason an evaporator coil will freeze is because the refrigerant temperature inside the coil has reached 32 degrees or lower. Numerous things can cause this such as:

    Dirty air filter
    dirty evaporator coil surface
    faulty blower motor
    faulty run capacitor on the blower
    excessively dirty blower wheel
    restricted return inlet
    stuck contactor in outdoor unit
    low refrigerant charge due to a leak
    unit is ran during cool outdoor ambient temps

    unless you're familiar with hvac equipment, i'd call a reputable service company.

    Later, jonesy

    Comment


    • #3
      Re: AC unit frozen?

      Originally posted by JONESY View Post
      The only reason an evaporator coil will freeze is because the refrigerant temperature inside the coil has reached 32 degrees or lower. Numerous things can cause this such as:

      Dirty air filter
      dirty evaporator coil surface
      faulty blower motor
      faulty run capacitor on the blower
      excessively dirty blower wheel
      restricted return inlet
      stuck contactor in outdoor unit
      low refrigerant charge due to a leak
      unit is ran during cool outdoor ambient temps

      unless you're familiar with hvac equipment, i'd call a reputable service company.

      Later, jonesy

      Jonesy,
      Thanks for the tips.

      I have a new air filter in the unit, changed it about 1 week ago.

      The unit outside it clean and the unit inside looks clean to me, nothing obstructing the intake.

      Not sure about the blower wheel.

      The unit outside seems to work fine.

      Might have to call someone tomorrow.
      Gus
      M40607

      Comment


      • #4
        Re: AC unit frozen?

        Originally posted by gigemaggs99 View Post
        Jonesy,
        Thanks for the tips.

        I have a new air filter in the unit, changed it about 1 week ago.

        The unit outside it clean and the unit inside looks clean to me, nothing obstructing the intake.

        Not sure about the blower wheel.

        The unit outside seems to work fine.

        Might have to call someone tomorrow.
        Do call someone. Put simply it's either low air flow or low charge. They'll probably tell you it's low and you can top it off but plan to replace your system very soon. Topping it off will not last long and it can't be done more than once. It's not worth finding the leak cause it's probably in the unit outside or in the evaporator. Niether of which is worth it for a 25 yr old unit. Besides, you'll save a ton on efficiency. If you have or want to upgrade the furnace with a variable blower, you may aslo get the 1500.00 tax CREDIT. Top off will limp you along but think of the future around the corner.

        Comment


        • #5
          Re: AC unit frozen?

          Do you know what the going rate is to replace the thing? Do I need to replace the inside and outside unit? Or is it one or the other? I know you can't give me exact prices but can you give me a ball park figure(s) so I know I'm not getting ripped off?

          Thank you.
          Gus
          M40607

          Comment


          • #6
            Re: AC unit frozen?

            gigemaggs99

            Ask some of your neighbors if they know a good Air Conditioning and Heating company for service? It may be something simple so for right now try to find the problem. Did the temp outdoors fall below 70F overnight?

            Today after thawing and most likely making a little mess of water on the floor, did things seem to be working OK again? Do look at everything you can see after running your AC some. Do you notice any icing at all anywhere?

            Having a good tech come out and check things over is always a good idea even if there aren't known problems. Sometimes something may be overlooked that can make a big difference on efficiency. If any of your return grills (air is sucked into them) got blocked in any way air flow is lowered. If you close dampers in your supply registers (air blows out of them) that can cause issues. Sometimes even the type of air filter(s) can be too restrictive.
            Last edited by Woussko; 08-02-2009, 12:36 PM.

            Comment


            • #7
              Re: AC unit frozen?

              If you want the tax credit you'll have to buy a furnace and the condensor/evap package or already have a variable speed furnace. If you want the condenser, you have to get the evap as well to achieve the 13 seer law. You'd want to do the line set as well especially if you switch to the newer 410a.
              You would want a whole new AC system also cause don't forget, you proabably have a leak. Have a tech confirm it's low and stop. Don't pay to find out you need to replace it any way. A leak could be anywhere and replacing it all prevents this from being a concern.

              Comment


              • #8
                Re: AC unit frozen?

                Originally posted by gigemaggs99 View Post
                Do you know what the going rate is to replace the thing? Do I need to replace the inside and outside unit? Or is it one or the other? I know you can't give me exact prices but can you give me a ball park figure(s) so I know I'm not getting ripped off?

                Thank you.
                As far as price, it's probably going to depend on unit, area, quality, warranty. There is no way to help you there. BBB, personal recommendation, multiple quotes. A good company won't sell you, you'll instead buy from the one your most comfortable.

                Comment


                • #9
                  Re: AC unit frozen?

                  how much money you got? breid

                  Comment


                  • #10
                    Re: AC unit frozen?

                    Check the blower. I have seen insulation from inside the blower cabinet come loose many times and obstruct the airflow to the point that the coil would turn into an iceberg. I think they were Rheem air handlers.

                    Comment


                    • #11
                      Re: AC unit frozen?

                      Originally posted by gusty60 View Post
                      Check the blower. I have seen insulation from inside the blower cabinet come loose many times and obstruct the airflow to the point that the coil would turn into an iceberg. I think they were Rheem air handlers.


                      Funnny I just saw this the other day on a rheem!!!!

                      Comment


                      • #12
                        Re: AC unit frozen?

                        Originally posted by gusty60 View Post
                        Check the blower. I have seen insulation from inside the blower cabinet come loose many times and obstruct the airflow to the point that the coil would turn into an iceberg. I think they were Rheem air handlers.
                        I had a trane XE furnace do this yesterday

                        Comment

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