1. On some models, the air intake has an automatic temperature control system, which is controlled by vacuum on carburetor and PM models, or by a wax tank on all other fuel injected models. A flap in the air intake directs warm air from the exhaust manifold, or cold air from the atmosphere, depending on the air temperature.
2. To test the temperature control system on carbureted models and PM engines, disconnect the regulator hose from the adapter in the brake booster hose and plug the adapter. Start the engine (cold), and let it run at high idle for a few minutes. Remove the air filter cover, reconnect the regulator hose to the adapter - the control flap should move to the fully open position allowing only warm air to pass through. If the flap remains closed, connect the adapter to the vacuum chamber with a hose - the flap should now open. If so, the temperature control valve in the air filter is faulty, but if the flap remains motionless, the vacuum chamber is faulty.
3. On all other engines with a fuel injection system, the control flap must be removed to verify operation. Loosen the screws and remove the block from the air filter housing. Immerse the unit in water below 30°C, the flap should move to the warm air position. Heat the water to a temperature above 38°C, the flap must close the warm air channel. If necessary, the inlet air temperature control unit can be removed by detaching the flap and pushing the unit through the hanger.
4. On all models, check that the flap moves freely.
Visitor comments