Cologne, Germany – 10 August, 2026 – The customer reported that the vehicle’s cabin blowers were only blowing hot air – on both the right and left sides. The technician investigated using a diagnostic tool, showing a fault with the servo motor V158. This is an automatic climate control actuator used in VAG vehicles – including SEAT. It adjusts the mixing flaps in the Heating Ventilation and Air Conditioning box to regulate the driver’s side cabin temperature. Ultimately, the vehicle’s climate control cooling had failed. 
 

Solution 
 

Because the vehicle has three servo motors clustered together, the technician initially struggled to pinpoint the exact location of the V158. Thanks to ALLDATA, however, the unedited OEM repair instructions showed the location and correct step-by-step guidance. 
 

What is an HVAC system? 
 

The HVAC system is responsible for the complete climate control system in a car – it manages cabin temperature, filters air being brought inside the vehicle and clears window condensation/fog. 

To heat, hot engine coolant travels through a tiny heater core to heat the cabin air. For ventilation, a blower fan and adjustable vents circulate fresh or recirculated air through the cabin. Switching to air conditioning, a multitude of components – including compressor, condenser and refrigerant – combine to extract heat and humidity. This blows cold air through the vents and cooling the inhabitants. 
 

ALLDATA’s facts and figures 
 

ALLDATA provides the latest, unedited technical information – directly from the vehicle manufacturer (VM). This includes TSBs, recalls, and technical updates that are not always clearly identified in standard documentation. With data from 44 VMs and more than 167,000 unique combinations of make, model, year and powertrain – representing 97% of the European car parc – ALLDATA is a vital workshop companion. 

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