DESCRIPTION
The Hot Air Intake (HAI) system adds hot air to the carburetor in cold weather to improve driveability and prevent carburetor icing. The carbureted Corolla and Tercel models use a Hot Idle Compensation (HIC) valve to control the opening and closing of the HAI diaphragm. Pickup models use a thermal valve to operate the HAI diaphragm.
OPERATION
When intake air temperature is low, the vacuum valve is closed and the intake manifold vacuum will act on the HAI diaphragm. This causes the diaphragm to pull up and close the air control valve. As intake air temperature rises, the HIC valve or thermal valve opens, dropping the air control valve and allowing unheated air into the air cleaner.
AUTOMATIC HOT AIR INTAKE
- Visually inspect all hoses and connections for cracks, leaks or damage. Remove air cleaner cover. On Pickup models, cool the thermal valve by blowing compressed air on it. On all models, when engine is cold, check that the air control valve closes the cool air passage at idle.
- Reinstall the air cleaner cover and warm engine. Check that the air control valve opens the cool air passage at idle. If system does not respond properly at given temperatures, check air door or linkage for binding. Replace thermal valve or HIC valve as necessary.
| Application | Closed Temp. °F (°C) | Opened Temp. °F (°C) |
|---|---|---|
| Pickup | 86 (30) | 113 (45) |
| Tercel Sedan | 79 (26) | 93 (34) |
| Tercel Wagon | 72 (22) | 84 (29) |
| Corolla (Carbureted) & Corolla FX | 72 (22) | 84 (29) |
HOT AIR INTAKE SYSTEM OPERATING TEMPERATURES
