Capteur de température d'évaporateur défectueux

The sensor measuring the temperature of the evaporator core in the cabin, whose real job is not comfort but stopping the evaporator freezing. Air passing over the core deposits condensation; if the surface drops below freezing that water turns to ice, blocks the core, and airflow collapses. The system cycles the compressor against this reading to keep the surface just above freezing.

So a fault here presents as a climate complaint rather than an electrical one. Reading too warm, the compressor runs on until the core ices and the vents deliver almost no air at all — a fault that clears itself after the vehicle stands and the ice melts, then returns, which reads like an intermittent electrical problem and is not. Reading too cold, the compressor is cut early and the air is never properly cold.

Its position makes access the main cost. It sits in the ducting against or inside the evaporator core, deep in the dashboard, so the sensible order is to prove the fault thoroughly before committing to the work. Compare its reading against vent temperature with the system running — a sensor reporting a plausible value that does not track what the vents are actually delivering is the finding, and no circuit test will show it.