Summer is in full swing and the last thing you want is a broken air conditioner. Here are a few things I have learned over the years to keep your A/C working so there is no need to call the repair man. I should say that I do not know how an A/C unit works or all the technical terms.
The filter is a big key in how your A/C functions. You should replace your filter according your your A/C instructions. If you have no idea then the best thing to do is replace it once a month or every other month at the most. When the filter is full air cannot pass through. This makes it so air can not circulate with in the unit. This can cause many issues one of which is the unit not working efficiently leading to higher bills. This also can cause the unit to freeze up. Which is what I'm willing to bet is the main reason most A/C repair men get called.
The big freeze (as I like to call it) happens when your unit is running constantly to keep up. My idea on how this happens is this. If you have a dirty filter and the air can't circulate then condensation builds up and then begins to freeze. And you can't push air through ice. So, the first thing to do when your unit is not blowing cold air is to turn it off for a couple of hours. While it is turned off find your filter and replace/clean it. You might have to leave it off for some time to get the ice to melt all the way. After several hours (2-4) turn your unit back on and see if you have cooler air. You also might want to check for water from the ice melting and clean it up. It can cause quite a bit of water damage if you don't catch it. If it still doesn't work at this point then call the repair man.
The big freeze happened just a few weeks ago to us when we got back from our vacation. The unit was on constantly trying to cool the house from 88 (vacation setting) down to 75. It happened last week to my dear friend. She already had the appointment set with the repairman and was calling me to complain about how hot it was. I suggested she turn it off for a few hours. Sure enough, it worked and she cancelled her repairman and saved some money.