Smart ForFour Climate Control Failure: Fix Guide

Had a similar issue with my Smart Fortwo 2018. Being someone with moderate car repair experience, I initially thought it was the heater core, but it turned out to be much simpler. The workshop diagnosed a faulty cable connection affecting the temperature regulation system. The blower motor was working fine, but the connection issue prevented proper communication between the dashboard panel controls and the heating components. They had to partially disassemble some interior trim to access and repair the wiring. Total repair time was about 2 hours and cost 95€, which included diagnostic and repair work. The air circulation system works perfectly now, and the heating response is immediate when adjusted. Before suggesting more specific solutions, could you share: Does the error code appear consistently? Have you noticed any changes in blower motor sound? Are there any unusual sounds when adjusting temperature settings? Does the issue occur more during specific weather conditions? These details would help identify if your issue matches what I experienced or if it might be something different.

Thanks for sharing your experience. My vehicle has 148280KM and just had its annual service last month. Yes, the error code appears consistently every time I start the car. The blower motor sounds completely normal, no unusual noises when changing fan speeds. Regarding temperature adjustments, there is a slight clicking sound when turning the dial, which seems new. The windshield fogging has become worse lately, especially during cold mornings, despite the air distribution settings being at maximum. Already checked the fuses and they seem fine. The air circulation feels weaker than before, even at highest settings. Given the similar symptoms you described, I will have the workshop check the wiring connections first before looking into more complex issues.

Thanks for those additional details. The clicking sound you mentioned when adjusting temperature actually rings a bell, I had that exact same symptom before the wiring issue was discovered in my Smart. Given that your vehicle has higher mileage, the temperature regulation system might have developed similar connection issues due to normal wear. The consistent error code and new clicking sound strongly suggest an electrical connection problem rather than a mechanical defrost air distribution flap failure. The increased windshield fogging despite maximum settings typically points to compromised climate control functionality, which aligns with failing electrical connections. The ventilation system capacity being reduced even with normal blower motor sounds further supports this diagnosis. When the workshop fixed my Smart, they found the wiring harness near the climate control module had some deteriorated insulation, causing intermittent connection issues. The repair involved replacing a section of the wiring harness and ensuring proper connections to the control module. One thing to specifically request when you take it in: have them check the wiring connections between the temperature regulation module and the heater control valve. This area was the culprit in my case.

Based on your reply and confirmation about the wiring connections, I will definitely have the workshop focus on checking those areas first. Your experience with the HVAC unit issues sounds nearly identical to what I am experiencing. The clicking noise during temperature adjustments and the error code pattern really help confirm this might be an electrical rather than mechanical problem. This actually makes me feel better about the potential repair costs, since dealing with wiring should be less expensive than replacing major components of the ventilation system. I will specifically ask them to inspect the wiring harness near the climate control module and check the connections between the temperature regulation module and heater control valve. The windshield fogging has become quite bothersome during my morning commute, so getting this fixed soon is a priority. Will schedule an appointment with the workshop tomorrow and have them run a full diagnostic. Thanks for helping me narrow down the likely cause, this should save both time and money by focusing on the most probable issue first.