L12 Climate control unit cools too much
- Make
- Alfa Romeo
- Model
- 156 Factory Service Manual
- Year
- 1997–2002
- Section
- Climate control › L12 Climate control unit cools too much
L12 Climate control unit cools too much
The control unit regularly operates the fan which sends air to the passenger compartment in accordance with the pre-set flows, but this air lowers the high temperature in the passenger compartment too much
This fault may be accompanied by a sudden increase in the temperature of the air sent to the passenger compartment
This is due to the operation of the system which switches off the cooling circuit if the temperature at the evaporator decreases too much.
| Step | Test procedure | Result | Action |
|---|---|---|---|
| 1 | CHECK USING 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. Check, in particular, that the control unit is correctly set considering there is no frost sensor | OK | |
| Error detected in the control unit |
End of diagnosis | ||
| Failed dialogue with the control unit | Restore:
End of diagnosis | ||
| 1 | CHECK USING DIAGNOSTIC EQUIPMENT Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket. Check that there are no faults in the climate control unit. Check, in particular, that the control unit is correctly set to take into account whether or not there is a frost sensor: | OK | |
| Error detected in the control unit |
End of diagnosis | ||
| Failed dialogue with the control unit | Restore:
End of diagnosis | ||
| 2 | MIXING MOTOR CHECK Using the diagnostic equipment (Examiner or other instruments) carry out the active diagnosis of the mixing motor | OK | |
| Faulty mixing motor connection |
End of diagnosis | ||
| connection between climate control unit and diagnostic connector |
End of diagnosis | ||
| 3 | FOUR STAGE PRESSURE SWITCH CHECK Check the four stage pressure switchSee Test 5040BA Checking operation of air conditioner (temperature) | OK | |
| Pressure switch defective |
End of diagnosis | ||
| Connections not correct |
End of diagnosis | ||
| 4 | SYSTEM PRESSURE CHECK Check the system pressure: TESTSSee Test 5040B Air conditioning system (pressures) efficiency test | OK | |
| High pressure does not increase or low pressure decreases too much: insufficient fluid High pressure continus to increase: too much fluid |
End of diagnosis | ||
| 5 | CORRECT OPERATION CHECK Check that fault is no longer present | OK | End of diagnosis |
| Fault persists | Incorrect selection of diagnostic procedure |
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