AC still frozen!

[Joe]

Ok the tech came out today and I thought it was fixed. The tech chemical cleaned the coils and checked the freon and he claimed the coils were not that bad for it to ice up. The tech said it might be the blower slowing down but he was not sure. When he left the unit was cold coming out but now I went outside and the unit frozed up again! I dont know what it could be and I dont want to pay a ton. Any ideas before the next tech comes?

Thanks alot and Please help

Joe