Here's a breakdown:
* Blend Door Actuators: These small motors control the mix of hot and cold air directed to each vent. If the actuator for the passenger side is malfunctioning (stuck or failing), it might not be able to properly open the cold air path, resulting in only hot air. Conversely, a properly functioning actuator on the driver's side would send hot air.
* Vacuum Lines: Many older climate control systems, including those in 2002 Cadillacs, use vacuum lines to control the blend doors. Leaks in these lines can prevent the actuators from receiving the correct vacuum signal, leading to improper temperature distribution. A cracked or disconnected vacuum line is a common and relatively easy-to-fix cause.
* Blend Door: While less common, the blend door itself could be broken or jammed, preventing it from moving to allow the proper mix of hot and cold air. This usually requires more significant disassembly to fix.
* Control Head (Climate Control Unit): A problem with the climate control unit itself (the panel with the buttons and knobs) could send incorrect signals to the actuators. This is less likely but possible.
* Mode Door Actuator: This actuator controls whether air comes out of the vents, defrost, or floor. If it's malfunctioning, it could indirectly affect the temperature balance, though this is less likely to cause *only* a driver/passenger side temperature difference.
Troubleshooting Steps:
1. Check the obvious: Ensure the temperature controls are set correctly, and that the fan speed is adequate.
2. Listen for unusual sounds: While operating the climate control, listen for any clicking or grinding noises from the dashboard area. These could indicate a malfunctioning actuator.
3. Inspect vacuum lines: Locate the vacuum lines related to the climate control system (often found under the dash). Check for any visible cracks, breaks, or loose connections. This requires some disassembly, and it's advisable to have a vacuum diagram for your specific Cadillac model.
4. Test the actuators (advanced): This requires more technical skill and often involves removing parts of the dashboard. You'd need to test the actuators' movement using a multimeter or by applying vacuum to them directly (with extreme caution).
Recommendation:
Unless you're comfortable working on car HVAC systems, it's best to take your 2002 Cadillac to a qualified mechanic or auto AC specialist. Diagnosing the exact cause can be tricky, and improper repair can lead to further damage. They have the tools and experience to quickly identify and fix the problem.
