Air Valve Vacuum Motor Functional Test - Jeep 1987 Wrangler Workshop Manual

ENGINES
THERMOSTATICALLY CONTROLLED AIR CLEANER (TAC)
2. Trap Door Vacuum Motor 7. Reverse Delay Valve
3. Reverse Delay Valve 8. Air Valve
4. Vacuum Source 9. Heated Air
5. Thermal Switch 10. Ambient Air
85038
AIR VALVE VACUUM MOTOR
FUNCTIONAL TEST
With the engine off, detach the ambient air duct
at the air cleaner and observe the position of the
air valve. It should be fully open to incoming
ambient air (heat in the O F F position).
WARNING: Use extreme caution when the
engine is operating. Do not stand in a direct line
with the fan. Do not put your hands near the
pulleys, belts or fan. Do not wear loose clothing.
Start the engine and observe the position of the
air valve. It should be fully closed to incoming
ambient air (heat in the ON position).
Depress the throttle rapidly (1/2 - 3/4-position)
and release. The air valve should briefly remain
stationary and then move toward the heat O F F
position and back to heat ON position.
Loosely attach the ambient air duct to the air
cleaner and warm the engine to the normal
operating temperature.
Remove the ambient air duct and observe the air
valve. It should be either fully open to ambient air
or at a mixture position that provides the correct
inlet air temperature to the carburetor.
Stop the engine and connect the ambient air
duct to the air cleaner.
If the air valve does not function as described in
the test, inspect for:
• a mechanical bind in the snorkel
• vacuum hoses being disconnected
• air leaks either at the vacuum motor, thermal
switch, reverse delay valve, check valve,
intake manifold or vacuum hoses
If the air valve manually operates freely and no
hose disconnections or air leaks are detected,
connect a hose from the intake manifold vacuum
source directly to the vacuum motor and the
start engine.
B-247