If your outside condenser is frozen then follow these steps:
The first thing you need to do is turn off your air conditioner and let it defrost. This will allow you to look into the condenser and see what is going on so that you can adequately fix it.
There are several reasons why your air conditioner condenser might freeze.
The first is air flow. If your air conditioner condenser is not getting proper air flow, it can cause condensation to build up inside and outside the unit – this collecting of condensation, having nowhere to go, slowly lowers the temperature of inside the condenser which slowly freezes on the surface and inside.
If this is your problem, you can go in after the AC has defrosted and work on cleaning it out. Changing dirty filters or clearing any obvious obstructions could be all it takes to get your AC up and working again.
If this is not the case, or the AC still doesn’t work properly after cleaning it, you could have a problem with your refrigerant.
A refrigerant leak can be caused by several things, such as a refrigerant being low or a crack in the seal.
If your refrigerant is low, replacing it could be the easy way of taking care of your heat problem. However, if there is a crack or a definite leak in your air conditioner, call a professional to take care of it right away.
Another thing that could cause your condenser to freeze is low outdoor temperatures – while this might seem silly when it’s 78 degrees or hotter outside during the day, if the temperature dips below 60 at night it could be causing your condenser to act up. Turn off your air conditioner at night and see if that helps with the freezing buildup.

For more information, please visit http://allweekairconditioning.com/air-conditioner-troubleshooting-how-to.html