1999 Chevy Blazer A/C failure after water pump replacement

At first, the A/C worked fine on this recently purchased used car. Then the car overheated due to low coolant from a water pump leak. The "Check Engine Light " came on. The water pump and thermostat were successfully replaced. Now the A/C does not blow cold air. Freon successfully added to the system; compressor comes on; lines get cold; but still no cool air from the vent. "Check Engine Light" diagnosis was emissions; code was cleared but still no cool air. Help!