Air Conditioning Refrigerant Distribution Valve

Routes refrigerant between the evaporators on a vehicle that has more than one — the rear air conditioning fitted to vans, larger estates, seven-seat vehicles and many SUVs, where a single compressor and condenser feed cooling units at both ends of the vehicle.

Its failure produces an unusually diagnostic symptom: cooling that works in one part of the vehicle and not the other. That distinction is worth knowing before booking anything, because the instinctive response to weak air conditioning is a regas — and a system genuinely short of refrigerant cools badly everywhere. One zone working normally is strong evidence that the charge is fine and the fault is in routing.

The valve is usually the last thing at fault. Its wiring runs the length of the vehicle to reach a rear unit — under sill trim where seat rails and anchor bolts are fitted, or along the floor of the load area — so it is crushed, soaked or unplugged by work that has nothing to do with air conditioning far more often than the valve itself fails.