I have a Carrier Gas Pack Model 48GS that was installed in 1999 and has stopped cooling the house. I discovered that the outside circuit breaker flipped off so I rest the breaker and the thermostate. The unit clicked on and the fan was running but no cool air was coming out the ducts. The breaker switched off again but the fan stayed on low. I flipped the braker on again and the fan switched to high but still no cool air. I was also unable to turn the fan off without turning off the breaker. A service tech is coming out this week. Any suggestions to what I may look for?