Air conditioning coil icing and freezing

is usually caused by a lack of refrigerant,

due to a refrigerant leak 

---

    I get lots and lots of inquiries about air conditioners and heat pumps icing up the indoor coils and the large line to the unit in the air conditioning mode.
    This is usually caused by a lack of refrigerant in the system due to a chronic leak. The reason that the coils form ice is that when the system is short on charge part of the coil runs very cold and ice starts to grow. Once the ice starts to grow it is in insulator and keeps on growing until the coil and the refrigerant lines are one block of ice.

    If this happens continuing to run the equipment will damage the compressor and not provide any cooling. If this was caused by running the system on a cold night, the best way to remove the ice is to leave the indoor fan on and let the ice melt (expect a mess).

    Refrigerant leaks will not go away and there is nothing that you can add to your system that will stop it.  The only cure is to repair the leak. Usually when there is a refrigerant leak the oil that is mixed with the refrigerant will collect around the leak and attract dirt. Look for these stains and chances are good that is where the leak is (there can be more than one). We have seen many cases where a service company will keep adding refrigerant 22 (Freon) to a leaking system and claim that they cannot find the leak, but when the covers are removed the oil stains tell other wise.

    Other things that will cause or aggravate ice are clogged filters, bad fan motors, to many closed vents, dirty filters (never been changed), running the system when it is "too cold outside" (below 65 degrees F) with out modifying the system for cold weather operation, clogged capillaries or bad expansion valves. Somone recently wrote me complaining that their unit ices up when it rains allthough they blamed "humidity" the real cause was that the head pressure would drop to the point where the indoor coil would ice up. Do discount the possibillity that the outdoor unit was replaced by one that is larger without changing the indoor coil to a larger capacity.

    We have seen an epidemic of clogged capillaries on Rheem Ruud units on the indoor coil. The only fix is to replace the coil with one that has an expansion valve and watch the system work better than when it was new.

    We are currently working on a Rheem/Ruud unit that had a bad compressor and after replacing the compressor we found a bad reversing valve (hissing real bad with high suction pressure). We replaced the reversing valve only to find the the metering orifice is the wrong size or clogged inside (air conditioning mode). The system is running about 40 psi suction pressure which will ruin the compressor and reversing valve. The reason that we know this is we put a liquid line sight glass on the system and the sight glass is full but the indoor coil is freezing up. The hard part is going to be explaining to the home owner that this has been the cause of the problem all along. If they had just replaced the outdoor unit then the problem would have been worse and they would be out a few thousand dollars and still no cooling. We finally did repair the system after finding some crud caught in the orifice. We are recommending changing the system to thermostatic expansion valves because I am getting a foaming sight glass and 80 psi of suction pressure. Which means the system cannot be properly charged.

---

    If you heat pump forms ice outside in the heat mode click here. If you have water leaking problems click here to solve it.  For other heat pump problems click here.  For other heating system problems click here. To schedule service in the Baltimore Washington Area Feel free to use this fill out form.
 Any other questions feel free to contact us by any of the means below. good luck Scott.
    If you were looking for Ice Machine or maker repairs click here.

---

We service and repair the following brands:
American Standard, Amana, Arco, Arco-Air, Bryant, Carrier, Coleman Evcon, Comfortmaker, Day/Night/Payne, Dunham-Bush, Fedders, Fredrich, Goodman, General Electric, Hotpoint, Heil, Intertherm, Janitrol, Kenmore, Lennox (Armstrong, Johnson Air-Ease), Miller, Modine, Nordyne, Rheem/Ruud, Sears, Stewart Warner, Trane, Williams, White-Westinghouse, Whirlpool, Weil-Mclain, York, (Frasier Johnson/Borg Warner) and others.

---

Written By:  Scott Meenen N3SJH of:
G&S MECHANICAL SERVICES.
Specializing in Mechanical, Controls and Electrical Modifications Of
Heating, Air-conditioning, Refrigeration, Cold storage,
Ice Production and Food preservation.
Anything having to do with Heat and Energy.
Serving MD, DC, and Northern VA.
Contact us by pager: 1-877-467-2914

---

                 This text written by: Scott Meenen * G & S Mechanical