C4 Corvettes use two separate components to handle the HVAC control duties. The control unit or control head that is visible in the dash and the programmer, hidden from view under the dash above and to the right of the accelerator pedal. One of the programmers duties is to direct engine vacuum to the appropriate actuators to select mode, recirculate, and vent. Programmers on all C4's become problematic with age. But, the 96 model programmers have a unique design feature that causes them to be more problematic than other years.

This feature is rubber nipples molded to the ends of the programmers vacuum connections. These nipples soften with age and will collapse under vacuum. Depending on which connections collapse, when, and to what extent you will see many different symptoms. The most common that most 96 Vette owners just live with is slow response when switching modes. Response times as long as 30 seconds have been noted. This is not normal and the switch should take 1-3 seconds when the system is functioning properly. The system may also work normally on first start up and then degrade as connections begin to collapse. The system may get stuck on one mode or in between modes.

The repair is simple. Remove the programmer. Cut the nipples off leaving only the rigid plastic tube connectors. Bypass the original soft connector with lengths of vacuum tubing. Here is a link to a basic how to on our website. The site has pictures of the programmer, the connector in question and the required modifications. Enjoy.

http://cadillacrepair.biz/96-corvette-ac-weak-airflow-from-vents/

Russell Boulding
Owner
RB Auto Service
Pinellas Park, Florida, USA