A-Coil is Frozen solid and line out to central air is covered in ice

Question

Last week we had a problem with our central air, call AHS and a guy came out. The problem was that the fan motor on our central air unit was shot. It kept kicking out, screeching and not cooling. So they replaced that. They checked the freon level and that was fine.

Now the A-Coil has started to freeze up along with the line out to the AC unit.. I 've melted the thing two times so far. I let it melt from 6 last night to 6 this morning with the fan on blowing ambient air at the coil. I then turned it back on and when I got home it was frozen again. I changed the filter last week so I assumed maybe it was too restrictive so I changed it out for a normal ACE pleated filter after the first time. So #1 they said the freon/refrigerant level was ok last Friday. #2 The filter is clean and the blower seems to be working fine. The whole duct system was cleaned 6 months ago. Any Idea's??

Answer 1

The a coil might be dirty and need cleaning or the blower motor is intermittent.  

Answer 2

Sorry, but I don't think they got the refrigerant charge correct. This may take another company, or at least a different tech to finish the job. Don't be afraid of asking for a second opinion. Good luck.

Answer 3

The main reason the coil and lines are freezing is due to low airflow across the coil. Can you feel air from your registers?  If not, and you changed the filter then I would assume the coil itself may be durty.

Answer 4

How about possibly an incorrect fan motor?

Low airflow or low on refrigerant.

Answer 5

Are you sure they install the correct sized motor?  Same horsepower, and RPM.  Is the motor turning in the right direction?  If the motor is turning in the wrong direction it will still put out air but not as strongly as it would in the correct direction.  Was the blower wheel reinstalled in the right direction?  On a 2 sided blower wheel it can be put in in the wrong way.  Contact the company that serviced your unit and have them send someone else back out and check everything over.  Don't be afraid to ask questions on what he is doing.  If you are asking questions the tech is more likely to do a better job and not as likely to accidentally overlook something.

Answer 6

It sounds like the air is still restricted.  Have you tried to run without the filter to see if it freezes up  if it doesn't then its the air filter is too coarse.  Also it may have been under charge I would have them come back out and check the pressure and if its low that would do it and you may have a small leak then

Answer 7

the refrigerant charge is probably off,  if they go by a pressure like 68 or 70 psi, they still need to check the superheat on the unit, you normally are looking for 5 to 15 degrees of superheat depending on a few different factors,  make sure the coil is completely defrosted before you have the tech back out, if the coil is frosted over, they will not get a true reading

Answer 8

the contactor for the outside unit can be sticking this will cause a freeze up too.

Answer 9

It will freeze if the evaporator fan isn't running.

Answer 10

Get the brainiac out there that charged the unit to come back and make sure the low pressure side is 68.5 PSI. This will give you 40 degrees across the A-coil if you are using R22.