Temperature Control Lock-Out Valve & Switch
WARNING: This page is about a different car, the 1994 Mercury Grand Marquis and 1994 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
The temperature control lock-out valve and switch is a combination vacuum valve and single-pole, single-throw switch. Switch is located on heater inlet hose in engine compartment. See Fig 1 . The thermal element of switch contacts coolant.
When function lever is in FLOOR position and engine is cold, blower cannot operate and outside/recirculated air door is held in recirculation position. When coolant temperature reaches about 120°F (49°C), electrical switch contacts close, allowing blower operation and outside/recirculated air door to move to outside air position.