P0D73: Air Conditioning Compressor Control Module Internal Temperature Sensor A Circuit Low
What to do
Air conditioning may work normally in mild weather and cut out when it is hot. On a heat-pump car the same applies to cabin heating in very cold weather. The car drives normally throughout.
What this code means
The circuit for the temperature sensor inside the air conditioning compressor's control module is faulty.
This measures the module's own internal temperature, not the refrigerant and not the cabin. A module that switches hundreds of volts to drive a motor generates real heat in a sealed box, usually mounted on or beside the compressor itself — one of the hotter places on the car.
So the sensor exists to let the module protect itself by derating, and the visible effect of that is air conditioning that works in mild weather and fades in hot weather, which is exactly when it is wanted and exactly the pattern people describe as "it just isn't as cold as it used to be".
Note the dataset runs Internal and Temperature together in P0D74's title. That is a transcription slip in the source; the corpus writes the space, as the second source does.
At or below the lower limit — usually a short to earth, or an open in the sensor's supply.
Likely causes
Start here
- Failed control module · specialist
- Corroded or loose connector · specialist
- Open circuit in sensor wiring · specialist
Less common
- Faulty electric air conditioning compressor · specialist
- Damaged wiring harness · specialist
Symptoms
Components involved
Information, not instruction
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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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