Your A/C, your fan, and one blown fuse

P0645, P0657 and P0480 describe three different things on paper — an A/C compressor clutch relay circuit, a general actuator supply voltage fault, and a cooling fan relay circuit. In our data they turn up together often enough that treating them as three separate repairs is usually the wrong instinct.

What the codes actually mean

Each of these covers a relay circuit: the ECU commands a relay to switch power to something — the A/C clutch, the radiator fan, or a broader "actuator supply" that several accessories can draw from depending on the platform — and the code sets when that circuit does not respond the way it should. None of these codes describes the accessory itself failing. They describe the switching circuit that powers it not behaving correctly, which is a different, usually cheaper, thing to fix.

What the telemetry says

Those are P0657's companions specifically, and the same pattern holds from P0480's side: it carries P0645 at 48.43%, P0657 at 40.26%, P0481 at 25.08%, P0335 at 20.35% and P0201 at 20.20%. A third to nearly half of scans carrying any one of these three relay codes also carry at least one of the others. A radiator fan and an A/C compressor clutch have nothing mechanically in common with each other — no shared belt, no shared mounting, no shared moving part. What they can share is the fuse box or relay panel that feeds both of them, and on many platforms, a single blown fuse or a corroded relay-box connection is enough to knock out several accessory circuits at once, each one reporting its own separate code.

P0226 — a throttle/pedal sensor supply voltage code, distinct from the pair-sensor cluster covered elsewhere on this blog — and P0335, a crankshaft position sensor code, appear at meaningfully lower but still notable rates. Read those as the same shared-supply story stretching a little further: a fuse or relay-box fault broad enough to affect several actuator circuits can graze sensor supply circuits on the same panel too, without every affected system necessarily being an actuator.

Why the repeat rate matters

P0645 alone accounts for 7,133 scans across 3,160 vehicles in our data — 2.26 scans per vehicle on average, noticeably higher than a one-and-done fault. That repetition is consistent with a connection that fails intermittently rather than one that fails once and stays failed: a corroded relay socket that makes contact most of the time and drops out under vibration or heat will set the code, seem to clear on its own, and come back.

One make stands out on P0657

Renault accounts for 65.2% of P0657 scans — 15.5 times its 4.2% share of the fleet overall — with the Kwid making up 46.38% of the vehicles we could identify. If you are working on a Renault Kwid and see this code, the shared-relay explanation is worth checking first, not last.

Why the fan matters more than the others

An A/C compressor clutch that will not engage is an inconvenience. A radiator fan that will not run is a reason to check before your next drive, not after it.

What to do next

Check the fuse box and relay panel that feeds these circuits before testing any individual component — pull and inspect the relevant relays and fuses for corrosion or a loose socket, and check for a shared ground point serving that panel. If the fan is among the affected circuits, physically confirm it runs before relying on the car for a longer trip. Only once the shared electrical supply checks out clean does it make sense to test the individual relay coils, the A/C clutch itself, or the fan motor.