A freezing air handler is caused by one of two things:

 

A. Low freon - This is the likely cause. You had it topped off a month ago for the same problem, and it fixed it. Now, you have the problem back. This is the most likely cause.

 

B. Insufficient airflow through the air handler.  - This is less likely, but if you have a severely plugged a/c filter or a weak fan, the coils of the air handler will freeze. I doubt this is your problem, but it is technically possible.

 

If you rent, it's no big deal. Call and have them fix it. If you own, the best thing is to shop around. Most compainies are going to try to sell you a complete new system. It's sort of like transmission shops that way. Ask a lot of questions before scheduling a service call. Know a little about your a/c unit before calling too. (Age, make, etc) It does make a difference with how service companies treat you.

 

Finally, keep in mind that winter is coming. Consider getting a window unit for the hot days remaining, and putting off the service until later. The winter months are off peak season for a/c companies, and they are more willing to negotiate because they have a lot less work. What may cost you a lot in the summer may not cost so much in the winter.

 

Hope this helps.

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