Written I was a bit surprised to see this question, since this should be readily available information elsewhere, so I did a short search to see if there is a problem finding out the answer.  It turned out there is, in that there are a lot of incorrect or incomplete answers out there.  The best answer I came across was this:"All air conditioners try to freeze up, that is the goal of the refrigerant... to chill.It is the design of the system that prevents this freezing up from occurring.There are three basic reasons for air conditioner freeze ups:Insufficient air flow Refrigerant charge Outdoor temperature1) The two most common causes of insufficient air flow are dirty filters and under sized ducts. A dirty filter limits air flow which in turn allows the cooling coil’s temperature to drop below freezing. Replacing the filter, monthly, usually alleviates this problem. Under sized ducts will also cause the system to freezeBecause it also limits the amount of air flowing over the cooling coil.

This results in lowering the coil temperature and allowing the humidity in the air to collect on the coil and freeze.2)Refrigerant charge. The refrigerant system teeters on a delicate balance. sanyo split system air conditioners reviewIf the system is not charged correctly, the system will not function properly. how to relocate hvac ductsThis malfunction may result in the poor cooling output and/or freezing up. dual fuel hvac wiringOnly a qualified, certified service technician can properly test and charge a refrigerant system.3) Outdoor temperature. If night time temperatures are too low, the system will not operate properly, and freeze up may occur. The outdoor unit does not function well in temperatures below 60 degrees F. A special “ambient temperature” control must be installed to allow the unit to run properly in cool temperatures, or you may open your windows and save energy." 

(, Air Conditioning Freeze Up .)Too many of the answers given on the web assume it is low charge, when it most likely is poor air flow due to an obstruction, which can be the filter, the coil itself being dirty, blocked vents, closed or dampered vents, or incorrectly set fan speed.  It can also be a symptom of too much refrigerant charge.  If the first thing your A/C serviceman does is hook up a bottle of refrigerant to your system, get a new serviceman.  The amount of charge should stay constant if the unit was installed correctly, so the most likely cause is a dirty filter, and hooking up hoses and gauges will not fix that and will typically lead to some incidental degree of refrigerant loss, especially when done carelessly, compounding the problem. Keep your filters and ductwork and coils clean and you will eliminate most problems with freeze-ups. Written Written Freeze up?   Like ice on the evaporator?  Often times, it's low on refrigerant. 20,317 posts, read 15,073,405 times

25,901 posts, read 21,074,479 times 33,571 posts, read 32,296,961 times When a central air conditioner freezes up, what actually freezes is the condensor unit's evaporator coil. This is the part of the air conditioning system that transfers (evaporates) heat from the inside to the outside of the home. There are two primary reasons the evaporator coil may freeze, it can either be due to 1) restricted air flow, or 2) lack of sufficient refrigerant. Either way, the result is that the air conditioner's evaporator coil cannot operate to properly dissipate heat, and in effect 'overcools' itself. The result of this super-cooling is condensation (that's water formation), and eventually ice from that condensation as it cools below the freezing point. Yep, the A/C just turned into an old-school icebox. Basic Tips for AC Repair and Maintenance Originally Posted by Barking Spider Filter is brand new. he checked air flow and temp conversion etc. The unit is 12 years old and never used hard.

I never have my temp below 76 in the summer. Input and out put lines also freeze so does the tank inside the unit out side. Its a carrier high eff. Originally Posted by AksarbeN What ever he did seems to have made it worse. 2,322 posts, read 2,396,739 times Originally Posted by tinman01 Well contact him to return and 1. either fix it properly or 2. you will have someone else do it and he will eat cost of the service if it is determined that his initial work, indeed made things worse. 222 posts, read 301,003 times inexpensive fiberglass filtershigh dollar thick filters restrict too much air flowThe requested URL /discuss/duboard.php?az=view_all&address=105x5356678 was not found on this server.Your heat pump can freeze up any time of the year, not just during the cold winter months. Under normal operation, frost develops on the outdoor coils. When the frost begins to build up, the unit automatically shifts into defrost mode to melt the frost. If this defrosting mechanism malfunctions, ice can build up to a point that the heat pump freezes and ceases to function.

Learn what you can do and when a qualified HVAC tech is needed. Sometimes the unit itself is not the problem. One of the first things you can do if you notice ice buildup is to see if the water is coming from an external source. A leaky gutter above the unit or freezing rain can cause ice buildup that blocks airflow past the coils. Blocked air vents, clogged air filters and debris build up around the unit may restrict airflow. Clear away all debris surrounding your outside unit and move any items inside the home that are blocking your air vents. Change the filters every few weeks or months according to the manufacturer’s specifications. A qualified HVAC technician can troubleshoot a more complicated problem with your heat pump. In some cases, water accumulates inside the condenser because the slab underneath the unit shifts or settles. A technician can offer solutions for improving drainage. Technicians can check the unit’s automatic defrost controls for faulty or worn components.