See Figures 1 through 6
This system is not used on the 2.5L jeep engine (Premier models). The Premier engine uses the Thermostatic Air Cleaner (TAC), described earlier in this section.
All 2.2L, 2.5L Chrysler and 2.6L carbureted and EFI engines are equipped with a vacuum device located in the air cleaner air intake. A small door is operated by a vacuum diaphragm and a thermostatic spring. When the air temperature outside is 65°F (18°C) or lower on carbureted engines, or 115°F (46°C) or lower on throttle body injected engines, the door will block off air entering from outside and allow air channeled from the exhaust manifold area to enter the intake. This air is heated by the hot manifold. At 90°F (32°C) or above on carbureted engines and 140°F (60°C) or above on TBI engines, the door fully blocks off the heated air. At temperatures in between, the door is operated in intermediate positions. During heavy acceleration the door is controlled by engine vacuum to allow the maximum amount of air to enter the carburetor.
This system is critically important to the operation of carbureted and throttle body injected cars because, when the carburetor or throttle body handles cold air, mixture calibration will become incorrect (too lean). The result will be lean running (misfire and hesitation). Engine performance will deteriorate even more during warm up in cold weather. The carburetor will also be more likely to ice up in cool, damp weather. There may also be high emissions of hydrocarbons, as revealed by emissions testing.
See Figure 7
You'll need a hand vacuum pump or other source of measurable vacuum for this test.
- Remove the air cleaner from the engine and allow it to cool to 65°F (18°C) on carbureted engines and 115°F (46°C), or below, on fuel injected engines.
- Inspect all the vacuum lines associated with the system and replace them if they are cracked or broken or if they do not seal tightly at the connections.
- Apply 20 in. Hg (67.5 kPa) of vacuum to the inlet side of the temperature sensor, a small round device with two vacuum ports, one of which was connected to the intake manifold. Apply the vacuum to the port that was connected to the manifold. Observe the temperature door-it should close.
- If the door remains open, connect the vacuum source to the vacuum diaphragm on the temperature door. The door should close and then retest the system.
- If the door now closes, replace the temperature sensor. If the door still does not close, replace the air cleaner, as the temperature door vacuum diaphragm and door are integral parts of it.
REMOVAL & INSTALLATION
See Figures 4 and 6
- Remove the air cleaner. Note routing and then disconnect both vacuum hoses from the sensor.
- Pry the retaining clips off the sensor connections and discard them. Pull the sensor and gasket out of the wall of the air cleaner.
- Install the new sensor and gasket and fasten the sensor in place by forcing the new retaining clips all the way onto the vacuum connectors. Make sure to hold the sensor against the air cleaner by its outside diameter as you install the clips so as to compress the gasket.
- Reconnect the vacuum hoses securely and reinstall the air cleaner.