Porsche 928 Engine Compartment Lid Switch

If cylinder heads had been machined or ground, check that thermostat housing fits correctly afterwards. It must not be installed with tension. If necessary, correct by machining mounting bores.

19-10 Disassembling and Assembling Thermostat Housing for Cooling System


The cooling air which enters through the new front air dam is regulated from the radiator intake by cooling air control flaps actuated by an electric positioning motor.

The control unit for the flaps and cooling-air control is positioned beside the passenger seat.

The flaps are positioned by a linkage connected to the positioning motor crank. The crank position which corresponds to the flap position is stored mechanically ort a control disk integrated in the positioning motor. (0%, 30%, 100%).

Cooling-water temperature sender

Tightening torque: 30 Nm {22 ftlb)

Temperature switch, automatic Temperature switch, intake transmi ssion

Tightening torque: 40 Nm (30 ftlb)

Tightening torque: 30 Nm (22 ftlb)

Engine-compartment lid switch

Pressure sender, Frigen

Tightening torque: 30 Nm (22 ftlb) M 4 nut : 1 Nm (0.7 ftlb)

The output stage receives a square signal from the control unit. The output stage contains two mutually independent output-stage modules with separate protective circuits: each module controls a separate cooler fan.

If a fault occurs, the cooling-air flaps are opened to the 100% setting and the intact fan operates at full speed, while the faulty fan is switched off. A check is made approx.every 20 seconds to ascertain whether the fault persists.

1. Control unit

2. Pressure sender, Frigen

3. Engine fan

4. Output stage

5. Flap positioning motor

6. Temperature sender, cooling water

7. Erigine-compartment lid switch

8. Temperature switch, intake

Temperature sender, cooling water

Flap position

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