* Blend Door Actuator (Passenger Side): This is the most likely culprit. The blend door actuator is a small motor that controls the mix of hot and cold air. If it's malfunctioning or broken, it might not be able to direct hot air to the passenger side, even if the system's overall heating function is working. It's possible the actuator is stuck in the "cold" position.
* Vacuum Lines: The system might rely on vacuum lines to control the blend doors. A leak in these lines can prevent the correct operation of the blend door actuator. Check for any cracked, disconnected, or loose vacuum lines near the HVAC system.
* Blend Door Itself: While less common, the blend door itself could be broken or jammed, preventing it from moving to the hot air position. This would require more involved disassembly to diagnose.
* Mode Door Actuator: This controls the selection between floor, dash, and defrost vents. If it's malfunctioning and stuck on "cold," you might be getting cold air even if the blend door is trying to supply hot air.
* Heater Core (Less Likely): A blocked or failing heater core would usually affect both sides, but it's possible a partial blockage only affects the passenger side. This is less likely given you have AC working on that side.
* Wiring/Electrical Issue: A short circuit or faulty wiring to the passenger side blend door actuator could also prevent it from receiving power to operate.
Troubleshooting Steps:
1. Check the obvious: Ensure the temperature dial for the passenger side is turned fully to the hot setting and the fan speed is sufficient.
2. Listen for the actuator: When you change the temperature, you should hear a slight whirring or clicking sound from the actuator (likely located behind the dashboard). If you hear nothing, it's likely faulty.
3. Inspect Vacuum Lines (if applicable): Locate the vacuum lines related to the HVAC system and check for any damage or leaks. This often requires some searching in the car's repair manual or online forums dedicated to the Oldsmobile Intrigue.
4. Consult a Repair Manual: A repair manual specific to your 2000 Oldsmobile Intrigue will provide diagrams and instructions for accessing and testing these components. This is invaluable for diagnosis.
If you're not comfortable working on the car yourself: Take it to a qualified mechanic specializing in older vehicles. They'll have the experience and tools to diagnose and fix the problem efficiently. Describing the symptoms clearly will help them pinpoint the issue quickly.
