* Blend Door Actuator: This is the most likely culprit. The blend door actuator is a small motor that controls the amount of hot and cold air mixed for the cabin. A failing actuator can make a flopping or clicking noise as it struggles to move the blend door. If it's broken or jammed, you'll get no hot air, or inconsistent heating.
* Blend Door: The blend door itself could be broken or dislodged. This is often the *result* of a faulty actuator, but could also be damaged separately (e.g., from a previous collision). A broken blend door wouldn't be able to regulate the air flow, leading to no heat. The flopping sound might be the door itself rattling against the housing.
* Heater Core: While less likely to cause a *flopping* sound, a failing heater core could cause no heat. A leaking heater core would be noticeable by a sweet-smelling coolant odor in the cabin and possibly wet carpets.
* Low Coolant: If your coolant level is low, the heater core won't have enough fluid to heat. Check your coolant reservoir.
* Thermostat: A stuck closed thermostat prevents coolant from circulating to the heater core, resulting in no heat. However, a stuck thermostat would usually cause overheating as well.
* Water Pump: A failing water pump won't circulate coolant effectively, affecting heating. This is less likely to produce the flopping noise.
Troubleshooting Steps:
1. Check Coolant Level: The easiest thing to check first. Low coolant could be a symptom of a leak (heater core, etc.).
2. Listen Carefully: Try to pinpoint the location of the flopping noise. Is it definitely under the dash, and on which side? This can help narrow down which blend door actuator might be the problem (Windstars often have separate actuators for driver and passenger sides).
3. Inspect the Actuator: If you can access the actuator(s) under the dash (you may need to remove some trim panels), look for signs of damage or movement problems. You might even be able to manually move the blend door to see if it's free. Warning: Be careful working under the dash; some parts are sharp or fragile.
4. Check the Heater Core (if no obvious actuator problem): Look for leaks under the carpet and smell for coolant. This is a more involved repair.
In short: The flopping noise strongly suggests a problem with the blend door actuator(s). Replacing these is a relatively common repair for Windstars of that era. However, before jumping to conclusions, check the coolant level and listen carefully to the noise to confirm its location. If you're not comfortable working on your vehicle, it's best to take it to a mechanic.
