16 · Diagnostics

L11 Climate control unit works irregularly

Make: Alfa Romeo
Model: 156 Factory Service Manual
Year: 1997–2002
Section: Climate control › L11 Climate control unit works irregularly

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Fault diagnosisL11 Climate control unit works irregularly

L11 Climate control unit works irregularly

The control unit operates the fan which sends air into the passenger compartment normally, with the pre-set flows, but this air sometimes makes the temperature in the passenger compartment too low and sometimes too high.

Step	Test procedure	Result	Action
1	SYSTEM OPERATION CHECK Check that the system cooling is correct: See Test 5040A Air conditioning system (temperature) efficiency test	OK	Move onto step 2
1		The temperature decreases very slowly: insufficient fluid:	Re-pressurize the system: Op. 5040A10 End of diagnosis
2	CHECK WITH DIAGNOSTIC EQUIPMENT Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check that there are no faults in the climate control control unit	OK	Move onto step 3
		Another is detected in the control unit	Continue according to the instructions for the diagnostic equipment End of diagnosis
		Lack of dialogue with the control unit	Restore: the connection between the climate control control unit and the diagnostic connector the climate control control unit supply. (Wiring diagram E6020 AIR CONDITIONER ). End of diagnosis
3	SYSTEM PRESSURE CHECK Check the system pressure: See Test 5040B Air conditioning system (pressures) efficiency test	OK	Move onto step 4
		High pressure does not increase or low pressure decreases too much: leaks in the circuit	Locate the leaks Op. 5040A14 End of diagnosis
		High pressure correct, low pressure very high	Replace the expansion valve Op. 5040B30 End of diagnosis
		High pressure high, low pressure below normal	Clean or replace the drier filter Op. 5040A44 End of diagnosis
		Pressure trends irregular: pipes obstructed	Wash the system: Op. 5040A10 End of diagnosis
		Pressure trends irregular: evaporator obstructed.	Replace the evaporator: Op. 5040C60 End of diagnosis
4	CONDENSER CHECK Visually inspect the condition of the condenser: the heat exchange surface should not be dirty or fouled	OK	Move onto step 5
4		Condenser dirty	Clean the condenser if necessary, replace it: Op. 5040A40 End of diagnosis
5	CHECK CORRECT OPERATION Check that the fault is no longer present	OK	End of diagnosis
5		Fault persists	Incorrect selection of diagnostic procedure

‹ Prev L10 Climate control unit does not cool Next › L12 Climate control unit cools too much

Parts & tools for this job For 1997 Alfa Romeo 156

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