Kenmore Side by Side Refrigerator stopping

Question

My Kenmore refrigerator freezer side went completely warm and defrosted everything. After a couple of days it started working again. Two days later it was warm again and this time the whole refrigerator was not cooling. I called a tech who came out and said he thought it was the compressor and told me to call Sears which still had the warranty. I called Sears and of course it started working again the night before they showed up. When the tech showed up he said since it was running he couldn't check anything out and offered the solution it might be the defrost timer since it goes on and off the way it does. Is this true? Can the refrigerator not be tested if its running? I got the feeling that he was trying to put me off and wait for the warranty to expire ..which is does in a couple of weeks. He then wanted 132.00 to come out which he decided not to collect from me. He said I would have to call back when the refrigerator is down but there is no way to get service that quick from Sears. Any advice you can offer please? I'm not sure what to believe at this point. Thank you!