A/C Blowing HOT and Cold at the Same Time!

From : 8675309

Q: i took my 98 corvette into a chevy dealer for the following repairs replaced the headlamp actuator... found internal short on bcm warranty company denied claim... found brake fluid present @ ebcm and bpmv replaced both modules. manually bled and power bled bpmv... found underhood connector corroded - repaired circuit and removed connector... splice sl 8.695 parts... changed oil. when they returned the car to me the a/c was blowing hot much hotter than outside temperature out of the center and drivers side vents and nice and cold out of the passenger side vents. the technitian claimed he didnt touch anything a/c related but admitted the a/c worked fine the day before when he test drove it. i remember the same thing happened at another chevy dealer when they installed a starter. the service writer took it to the back and within five minutes brought it back working fine. he said the a/c just needed to be reset. unfortunately this tech didnt have a clue what to do. anybody have any idea what could be the fix for this thank you steve .