Used on 3A-C and 3E engines.
The hot idle compensation (HIC) system allows additional air to enter the intake manifold, maintaining a proper air/fuel mixture during idle at high temperatures. It also controls the vacuum supplied to the HAI valve, allowing heated air to enter the air cleaner during cold operation.
See Figures 1, 2, 3 and 4
- Check that air flows from the HAI diaphragm side to the carburetor side while closing the atmospheric port.
- Check that air does not flow from the carburetor side to the HAI diaphragm side with the atmospheric port open.
Check that air does NOT flow from the HAI diaphragm side to the atmosphere port while closing the carburetor side below these temperatures:
- 72°F (22°C) - 3A-C engines
- 79°F (26°C) - 3E engines
- Using a water bath, heat the HIC valve to above 84°F (29°C) on 3A-C engines or 93°F (34°C) on 3E engines.
Do not allow water to get inside the valve.
- Check that air flows from the HAI diaphragm side to the atmospheric port while closing the carburetor side.