Now that it has gotten warmer, I just tried to turn on the COOL function of my thermostat. The outside unit kicks on and starts running, but the fan is not blowing anything. This happened last year and my HVAC guy done something to the thermostat and it started working. I really hate to pay him another $100.
If there is a Fan setting on the thermostat make sure it is set to auto or try putting it to On and see if its workin then. Auto should allow the fan to turn on only when the outside unit is on as well. If all the Hvac guy did was last was mess with the thermostat and no one since has tampered with the wiring then it just sounds like the fan setting is turned off. The manual should help then.
I would also check to make sure your blower unit isn't turned off for some reason as well. There may be a switch located on the unit or the breaker could be tripped.
Best of luck, post back if you have more questions