* Blend Door Actuator (Passenger Side): This is the most likely culprit. The blend door actuator is a small motor that controls the flow of hot and cold air to each side of the vehicle. If the passenger side actuator is malfunctioning, it might be stuck in the cold air position, even when you've selected heat. This is a relatively common failure point in many vehicles.
* Blend Door Cable (If applicable): Some older models use cables instead of actuators. A broken or frayed cable could prevent the passenger side blend door from properly directing hot air.
* Vacuum Leak: The HVAC system may rely on vacuum to control some functions. A leak in the vacuum lines could prevent the passenger side from receiving the signal to switch to hot air.
* Clogged Heater Core (Less Likely): While a clogged heater core typically affects both sides, a partial blockage could cause a reduced flow of hot air to the passenger side. This is less likely to be the sole cause of the problem since the driver's side is still getting hot air.
* Restricted Airflow (Passenger Side): Something might be blocking the vents on the passenger side, like debris or a misplaced object. Check for obstructions.
* Faulty Temperature Sensor: A faulty temperature sensor could be providing incorrect information to the climate control system, resulting in an imbalance of hot and cold air distribution.
Troubleshooting Steps:
1. Check for Obstructions: Make sure nothing is blocking the vents or airflow on the passenger side.
2. Check the Blend Door Actuator: You might be able to access and manually move the blend door (after disconnecting the actuator) to see if it's freely moving. This requires some mechanical knowledge and might involve removing parts of the dashboard.
3. Listen for Actuator Sounds: When changing the temperature setting, listen carefully for the clicking sound of the blend door actuators. If one side is silent, that's a strong indication of a faulty actuator.
4. Check Vacuum Lines (if applicable): Inspect the vacuum lines for cracks, leaks, or disconnections.
5. Have a Professional Diagnose: If you're not comfortable diagnosing and repairing the problem yourself, take your Grand Caravan to a qualified mechanic or auto AC specialist. They have the tools and expertise to properly diagnose and repair the issue efficiently.
Without physically inspecting your vehicle, it's impossible to pinpoint the exact cause. However, the blend door actuator on the passenger side is the most probable suspect based on your description.
