Would overuse cause a residential a/c evap coil to freeze?

Question

We bought a new house three years ago. AC worked just fine. Day before yesterday the air coming out of the ducts was not as cold and it was running all day and night but would not bring the temp down to the level we had it set at. Today we had the a/c tech come out and he opened the blower in the attic and the lower half of both evap coils were frozen solid. He advised us to turn the system off and run the fan to defrost it, which idid. He thought the reason it was frozen was that we had it at too low a temp for too long. Its been in the 90's here for a few weeks and we had it set at 73. Is this a possibility or is the ice a symptom of a bigger problem? Its a split system with the other hald on the side of the house. He checked the outside coils for leaks and found none. After defrosting we are now running the system and it still does notseem as cold. Any suggestions or advice?

Answer 1

Open all your vent grilles, if the tech did not go ahead & clean the evap and condenser coils he didn't finish the job. Proper airflow is extremely important. He was right about placing too high heat load on the unit....



Depending on the metering device, he should have checked either the superheat or the subcooling.

Its not always a refrigerant problem,.... but if it is low, it went somewhere.... a competent tech can find the leak.



Honestly,.. it sounds to me like there is a TXV/distributor and the micro lines going to the bottom of the A coil have a restriction but the top is fine....

Answer 2

boy howdy, split system. i'm assuming the tech checked all the electrical controls and refrigerant levels. a faulty circuit board comes to mind, but also i would have to check the super heat levels and the air temp differences.



i feel certain you have already replaced your indoor filter and that the indoor fan is working correctly. other than refrigerant, that's about the only two ways indoor coils ice up. are your lines insulated? you can have heat exchange through a hot attic if they arent insulted.



tough call....i suggest cleaning or replacing your indoor filter and 2x check refrigerant level(s), (then we need to find the leak, if there is one.).



one other thing could be an air flow problem. if it's none of the other stuff, somebody needs to inspect the duct work

Answer 3

There are many things that will cause them to freeze up; high humidity, improper pressure, dirt. The thing that causes them to freeze most often is having them set higher than they can handle. An A/C needs a break. If the room is to big or the temperature is set to low it doesn't get a chance to kick off ( a necessary think to keep from freezing). Maybe you need a bigger unit.

Answer 4

I agree that the issue is probably air flow. Meaning is the filter clean, the evaporator coils clean, (do you have pets? and is the furace blower fan clean? Also even though it has been done, do a re-check of refrigerant levels. Good luck.

Answer 5

you need to get that back out there and tell him to check the refrigerant lvl.....sounds like you are running low