Automatic climate control with filter (IHKR/F3)
Scheme 6450.5

A=X18155	26-pin, white
B=X18156	26-pin, black
C=X18157	26-pin, blue

Pin Assignment X18155

Pin	Type	Description/Function	Connection
1		not used
2	E	Right heat exchanger temperature	Right heat exchanger sensor
3	E	Left heat exchanger temperature	Left heat exchanger sensor
4	E	Outside temperature	Outside temperature sensor
5	E	Evaporator temperature	Evaporator sensor
6	E	Setpoint, mixing air actuator	Mixing air actuator
7	E	Signal, independent ventilation	Relay box, independent heating/ventilation
8	E	Speedometer A signal	Instrument cluster
9		not used
10	E	Signal, independent heating	Relay box, independent heating/ventilation
11		not used
12	E	Terminal 58K	Light switch/lights
13	A	Supply voltage for function lights	IHKR/F3 push button unit
14	A	Supply voltage for mixing air actuator	Mixing air actuator
15	M	Ground for regulator in operating unit	IHKR/F3 operating unit
16	M	Ground for all sensors	All temperature sensors
17	M	Ground	Mixing air actuator
18	E	Push button unit lights	IHKR/F3 push button unit
19		not used
20	E	Signal, air condition ON	IHKR/F3 push button unit
21	E	Signal, recirculated air/AUC ON	IHKR/F3 push button unit
22	E	Signal, rear window defogger ON	IHKR/F3 push button unit
23	E	Function indicator, air conditioning ON	IHKR/F3 push button unit
24	E	Function indicator, rear window defogger ON	IHKR/F3 push button unit
25	E	Function indicator, AUC ON	IHKR/F3 push button unit
26	E	Function indicator, recirculated air ON	IHKR/F3 push button unit

E = Input, A = Output, M = Ground

Pin Assignment X18156

Pin	Type	Description/Function	Connection
1	M	Ground	Ground connection
2		not used
3	E	Interior temperature	Interior temperature sensor in IHKR/F3 operating unit
4	E	Setpoint, fresh air	IHKR/F3 operating unit
5	E	Setpoint, left blower	IHKR/F3 operating unit
6	E	Setpoint, right blower	IHKR/F3 operating unit
7		not used
8	E	Signal AUC ON	AUC control unit
9	A	Signal, air conditioning ON	Diode module
10	M	Ground	Ground connection
11		not used
12	E	Terminal 30	Fuse
13	E	Terminal 30	Fuse
14		not used
15	E	max. heating, right	IHKR/F3 operating unit
16		not used
17		not used
18	E	Signal	Relay box, independent heating/ventilation
19		not used
20		not used
21		not used
22	E	max. heating, left	IHKR/F3 operating unit
23	E	Terminal 15	Fuse
24		not used
25	E	Terminal 61	Unloader relay
26	E	Terminal 30 h	Generator

E = Input, A = Output, M = Ground

Pin Assignment X18157

Pin	Type	Description/Function	Connection
1	A	Voltage supply for actuators	all actuator motors
2	A	Voltage supply for actuators	all actuator motors
3		not used
4		not used
5		not used
6	A	Signal, recirculated air	Recirculated air flap motor
7	A	Signal, recirculated air	Recirculated air flap motor
8	A	Signal, recirculated air	Recirculated air flap motor
9	A	Signal, recirculated air	Recirculated air flap motor
10	A	Signal, fresh air	Fresh air flap motor
11	A	Signal, fresh air	Fresh air flap motor
12	A	Signal, fresh air	Fresh air flap motor
13	A	Signal, fresh air	Fresh air flap motor
14	A	Voltage supply for potentiometer	IHKR/F3 operating unit
15	A	RxD diagnosis line	Diagnostic connector
16	E/A	TxD diagnosis line	Diagnostic connector
17		not used
18	A	Signal, interior sensor blower	Interior sensor blower motor
19	A	Signal, auxiliary water pump	Auxiliary water pump relay
20	A	Signal, rear window defogger ON	Rear window defogger relay
21		not used
22	A	Signal, A/C compressor ON	Pressure switch B8y
23	A	Signal, air mixing	Mixing air flap motor
24	A	Signal, air mixing	Mixing air flap motor
25	A	Signal, air mixing	Mixing air flap motor
26	A	Signal, air mixing	Mixing air flap motor

E = Input, A = Output, M = Ground