Alfa HVAC Control Panel Issues and System Malfunction

I had nearly identical climate control issues with my 2004 Alfa 159 diesel. With some experience working on cars, particularly HVAC systems, I can share what worked for me. The symptoms were exactly like yours, inconsistent heating, AC not engaging, and an unresponsive control panel. After taking it to a workshop, they found corroded electrical connectors between the control unit and the blower motor. The temperature sensor readings were also inconsistent because of damaged wiring. The fix involved cleaning the electrical connectors and replacing a section of wiring. Total cost was 95 Euro for parts and labor. Since the repair, the climate control system has worked flawlessly. Before suggesting more specific solutions, could you share: Are you getting any specific error codes? Does the blower motor run at all? When did these issues start occurring? Have you noticed any moisture or water damage near the control unit? Electronic faults in these systems often stem from connection issues rather than failed components. Getting this additional information would help narrow down if your problem matches what I experienced.

Last service was completed at 138766 KM. Thanks for sharing your insights, I am getting error code P0532. The blower motor runs intermittently, mostly on the highest setting only. The issues started gradually over the past month, getting worse in the last week. I have not noticed any obvious moisture damage, but there is a slight musty smell when the system runs. The power supply to the control unit seems inconsistent, sometimes the display flickers before becoming unresponsive.

This error code P0532 indicates an AC pressure sensor circuit low input, very familiar with this one from my Alfa experience. The musty smell combined with the blower motor only working on high strongly suggests multiple issues in the HVAC system that align with what I encountered. The flickering display points to electrical problems beyond just the pressure sensor. In my case, the wiring harness connecting the climate control module had deteriorated near the blower motor resistor, causing similar intermittent operation. Key findings from my repair: Corroded wiring at the pressure sensor connection, Damaged blower motor resistor, Clogged drain causing the musty smell and potential electrical issues The repair involved: Replacing the AC pressure sensor (45 Euro), New blower motor resistor pack (85 Euro), Cleaning drain lines, Repairing sections of the wiring harness (60 Euro) Total repair was around 190 Euro plus labor. The system needs proper diagnosis with a scanner to confirm, but based on the matching symptoms, I suggest checking these components first. The flickering control panel often clears up once the electrical connections are properly restored. Considering your mileage, this timeline of failure matches the typical wear pattern of these electronic components in the HVAC system.

Thanks for the detailed explanation. Your solution makes sense given my error code and symptoms. I will get the pressure sensor checked first since that matches the P0532 code. The intermittent blower motor definitely sounds like a resistor pack issue as you described. The total repair cost of around 190 Euro plus labor seems reasonable compared to replacing the entire control panel, which I initially feared might be necessary. I will have my mechanic inspect the wiring harness and clean the drain lines while checking the electrical connectors throughout the system. The temperature sensor readings on my display have been erratic too, so having them check all those connections during the repair should help resolve the complete set of issues. I will schedule the work soon before the problems get worse. Will update once the repairs are complete to confirm if these fixes resolved my climate control troubles. Thanks again for sharing your experience with such a similar HVAC system problem.