Regarding the Foggy Windows:
* Clogged or malfunctioning drain: The AC system has drains to remove condensation. If these are clogged, water can build up and cause fogging. This is more likely to occur when using the AC.
* Leaking cabin air filter: A wet or damaged cabin air filter can lead to excess humidity inside the car.
* Poor ventilation: Not enough fresh air circulating can lead to a buildup of moisture from breath and perspiration. Ensure your ventilation system is properly functioning.
* Low coolant: A low coolant level can prevent proper heating, leading to cooler air that can't effectively clear the moisture from the windows.
Regarding the Intermittent Heater:
* Blend door actuator: This component controls the flow of hot and cold air. A faulty actuator can cause the heater to work intermittently or not at all. This is a common issue on many vehicles, including the Grand Prix.
* Heater core: A clogged or leaking heater core restricts or prevents hot coolant from flowing to the heater, resulting in weak or no heat.
* Thermostat: A faulty thermostat may not allow the engine to reach operating temperature, limiting the amount of heat available.
* Low coolant: As mentioned above, this is a crucial element for proper heating.
* Blower motor resistor: This component controls the fan speeds. A faulty resistor can cause the blower to run on only one speed or not at all.
* Blower motor: The blower motor itself could be failing. It might work intermittently or not at all.
* Wiring or fuses: Check the fuses related to the heater and blower motor. There might also be a wiring problem somewhere in the system.
Connecting the Two Problems:
The foggy windows and intermittent heater might be related, particularly if the issue stems from low coolant. Low coolant prevents effective heating, leading to increased moisture and fogging.
Troubleshooting Steps:
1. Check Coolant Level: This is the first thing to do. Low coolant is a common cause of both problems.
2. Inspect Cabin Air Filter: Replace it if it's dirty or wet.
3. Check Blower Motor and Resistor: Listen for the blower motor; if it's weak or makes unusual noises, it might need replacing. Check the resistor as well.
4. Check Fuses: Examine the fuses related to the heater and blower motor in the fuse box.
5. Test the Blend Door Actuator: This usually requires a diagnostic scan tool. If the actuator is faulty, it's often best replaced as testing and repair is often more involved than replacement.
6. Inspect Heater Core: This is more involved and may require professional help. Look for leaks or signs of damage.
If you're not comfortable performing these checks yourself, it's best to take your Grand Prix to a qualified mechanic for diagnosis and repair. They have the tools and expertise to pinpoint the exact cause of the problems.
