P0EC6: Air Conditioning Power Supply Relay Control Circuit/Open
What to do
Expect no air conditioning, and no cabin heating on a heat-pump car. The car drives normally. In warm weather watch for slower rapid charging too — on many cars the same compressor cools the battery.
What this code means
The control circuit for the air conditioning power supply relay is faulty.
A relay in a high-voltage climate system is doing something a conventional air conditioning relay never had to.
On a belt-driven system the relay switches a twelve-volt clutch coil. Here it switches — or commands the switching of — the several-hundred-volt supply to the compressor's inverter. That is a materially different job, because it must be able to isolate a high-voltage load, and because leaving it closed means leaving that load energised when the car believes everything is shut down.
Which is why this circuit exists separately from the compressor's own control. The compressor can be told to stop; the supply relay is how the car makes sure it has. A commanded stop that a faulty compressor ignores is exactly the failure the relay is there to end.
The practical consequence of losing it is simply no climate control — no cooling, and on a heat-pump car no heating either, because both run through the same compressor. On many vehicles it also removes battery cooling, so warm-weather rapid charging slows at the same time and nobody connects the two complaints.
The control circuit is open — no drive reaching the relay coil.
Likely causes
Start here
- Faulty module power relay · specialist
- Open circuit in control wiring · specialist
- Corroded or loose connector · specialist
Less common
- Control module driver failure · specialist
- Blown fuse or failed supply · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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