Porsche 928 Recirculation Flap

3.) Operation of Flaps

The vacuum servos regulating the flaps are activated by solenoid valves. The flap activation can also be checked in conjunction with the above mentioned test. If the test lamp comes on for a given valve (vacuum available) , the corresponding flap must be in the following position.

Footwell open Defroster closed Center vent open 1st step (switch must be in bottom position) Center vent open 2nd step (switch must be in bottom position) Mixing flap open Heater valve closed Recirculation closed

C /

yellow

F /

green

D /

orange

E /

brown

A /

red

A /

red

B /

blue

D.) Cold Start Over-Ride (Test Lamp and Ohmmeter)

The operation of the cold over-ride system will have to be checked, if the flaps cannot be activated in selector lever positions ECO, AUTOM and BI, or the flaps remain open in poa. DEF. (recirculation flap, footwell flap and center vent flap should be closed, heater valve and defroster flaps should be open).

Also, if there is complaint of "cold draft". At low outside temperatures when the engine is also cold, the cold start over-ride automatically directs all of the air from the heater/A.C. system to the defroster ducts. This is done to prevent cold drafts in the car before the heater warms up.

Checking

(warm engine see point D 2)

a) Remove both center console side trim panels. Check ground connection (brown) on left side of solenoid valve holder.

Connect ohmmeter (measuring range x 1, calibrated) between term. 5 (blue-yellow) of disconnected plug (S2) at control unit and body ground. (measuring coolant temp, sender resistance). Important I Pull off left plug of instrument cluster. Tester must show resistance greater than 285 ohms. If resistance is lower, coolant is too warm (see point D 2). Reconnect instrument cluster plug.

b) Connect test lamp between ground and plug (Si) term. 3 (green/blue), Plug remains connected on the control unit.

Selector lever at OFF pos. - ignition turned on. Test lamp should come on.

(Test lamp does not come on - check according to point A.)

TESTING CLIMATE CONTROL AIR CONDITIONER M 563 % -

c) Disconnect test lamp from ground and connect to ground rail of solenoid valves.

Test lamp should come on.

(Test lamp does not come on - check ground connections (wiring diagram) (BI) term. 9 - (S2) term. 3 - (B2) term. 2/3.)

d) Set selector lever to AUTOM or BI. (servo motor should run to top position, if necessary set temp, selector lever to 85° F)

Test lamp should go out.

(Test lamp does not go out - pull plugs (SI) and (S2) off of control unit one after the other - check servo motor position. If applicable, repeat test with a new servo motor (without installing same).

e) Run engine. When reaching a coolant temperature above 104° F, transmitter resistance = less than 285 ohms.

Test lamp should come on.

^ Otherwise check control unit.

2.) On warm engine - coolant temperature above 104° f.

a) Remove both center console side trim panels. Check ground connection of left solenoid valve bar. Connect ohmmeter (measuring range x 1, calibrated)

to term. 5 (blue/yellow) of disconnected plug (S2) and body ground,

(measuring coolant temp, sender resistance) Tester should show resistance less than 285 ohms.

b) Connect test lamp on connected plug (SI) term. 3 (green/blue) and ground rail of solenoid valves.

Program control at OFF pos. - ignition turned on.

Test lamp should come on.

c) Set selector lever to AUTOM or BI.

Set temperature selector lever to 85 ° F servo motor should run to top position. ,

Test lamp should come on.

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