Air condition freezing up

Make sure the condensate drain is clean and clear of any debris. With the indoor unit off, Remove the inspection panel and pour a gallon mixture of 10% Bleach to Water solution in the drain pan. Do not overflow the pan but check to make sure there is flow to the outside or drain. Clean out the drain hose if you have to.
A freezing coil is a sign of either not enough air going across it or not enough charge in the system. Check to make sure all of the return air vents as well as supply vents are in full open and unrestricted. If they are, you will need to have the charge checked. If this turns out good, have your technician install an anti-freeze kit. This kit will temporarly turn off the compressor unit for a short period when the sensor in the kit experiences a freezing condition. Then after a bit, it will turn on the compressor. It may not cool as much as it was, but it may get you thru.

Good Luck!