I have a split unit air conditioner.
The fan/compressor unit is a Kenmore N4A3. The unit is only about 5 years old.
The problem I'm having is the at times the air coming out in the house is not cold. When that happens, the fan outside is not running.
Then suddenly it will start running again. It has been going on a couple of days.
Any idea what I can check on the outside unit? I'm trying to avoid a costly service call if it something simple.
I'm typically pretty good at investigating and fixing things, but not real savvy about HVAC, so any input explained for beginners would be greatly appreciated.
Thanks, in advance!

It sounds like you have a loose wire. All you can do is to turn off the power to both units and check out the wiring. You have control wiring (24 volts) which drives the coils on different relays and most likely to give problems, and you have line voltage which is usually two hot wires to give you 240 volts. You will need a meter to check things out. Never try working on a unit without a meter because it tells you everything. Here are some diagrams: https://dl.dropboxusercontent.com/u/8010163/AC%20Wiring%20Diagrams.zip
https://dl.dropboxusercontent.com/u/8010163/How%20to%20use%20Test%20Equipment%20Service%20Manu al.pdf
It is very easy to figure out. The wires "Y" and "C" go to a straight cool unit outside to pull in the contactor to bring on power to cool. "R" which is usually a red wire is one side of the 24 volt transformer and "C" or common is the other side. "R" is switched in the thermostat to be sent to "Y," the contactor outside and "G," the fan relay inside to cool. Any loose screws on the thermostat will cause the problem you described, or a control wire chewed through by a dog or rat. Control wires have a brown plastic covering and are small wires. You should be able to find the problem.