Thunderbird V8-302 5.0L HO (1992)
Air Injection Vacuum Control Solenoid Valve: Description and Operation
Dual Thermactor Air Control Solenoid Valve
The Thermactor Air Bypass (TAB) and Thermactor Air Diverter (TAD) solenoids control whether or not vacuum is applied to the TAB and TAD
valves. The Engine Control Assembly (ECA) controls bypass and diverter valve operation by providing circuit ground for the TAB solenoid and the
TAD solenoid.
When the engine is STARTED and its coolant temperature is below 50°F (10°C), the ECA will not ground the TAB solenoid. The TAB Valve
diaphragm remains closed by spring pressure, causing pump air to be bypassed to the atmosphere.
When coolant temperature reaches 50°F (10°C), the ECA grounds the TAB circuit and the TAB solenoid is ENERGIZED. Vacuum is applied to the
TAB valve diaphragm, the bypass valve opens and pump air is sent to the diverter valve. The ECA, at the same time, provides a ground for the TAD
solenoid circuit, which allows vacuum to be applied to the diverter valve diaphragm. This causes the diverter valve to direct pump air to the exhaust
manifold.
Once the engine is in CLOSED LOOP MODE, 190°F (88°C), the ECA removes circuit ground for the TAD solenoid. The diaphragm is CLOSED by
spring pressure, and pump air is redirected downstream to the catalytic converter.
