Faulty air conditioning refrigerant distribution valve

One of the valves that routes refrigerant between the branches of an electric or hybrid vehicle's air conditioning circuit has stuck, or its control circuit has failed.

This part exists only because an electric car asks one refrigerant circuit to do three jobs. A conventional system has a single evaporator and cools the cabin. An electric car's circuit must also chill the traction battery through a coolant heat exchanger, and on a heat-pump vehicle run backwards to warm the cabin. Those demands compete and arrive in combinations — cooling the cabin while chilling the battery during a rapid charge on a hot day is the hardest of them — so the refrigerant is routed rather than simply switched on.

Which is why a stuck valve does not produce "no air conditioning". It produces the wrong thing being cooled, and that gives it a distinctive signature: a cabin that will not get cold while the battery is rapid-charging, a battery that overheats only when the air conditioning is working hard, or heating that fails on a heat-pump car while cooling still works. Complaints that depend on what else the car is doing at the time point here, and they are routinely dismissed as intermittent.

Two failure modes need separating, because the standard gives them separate codes and the repairs differ. A control circuit fault means the command never arrived. A stuck valve means the command arrived and nothing moved — and no electrical test can see that, which is why the mechanical codes exist alongside the circuit ones.

Check the valve before the module. A seized valve makes the module's output driver exceed its current limit, so the car may store a driver fault that reads like a module failure — and a replacement module with the seized valve still attached reports it again within days.