Error Code P06A0 is defined as Variable A/C Compressor Control Circuit. This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II scanner, particularly those made since 1996 up to present. This includes vehicle models from, but not limited to BMW, Dodge, Ford, General Motors, Honda, Mercedes Benz, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

The Variable A/C Compressor Control Circuit works by engaging and disengaging the compressor at the right time, keeping the desired amount of temperature within the vehicle cabin. The ECU (engine control unit) gets the voltage signals from different components, detecting possible malfunctions within the system.

The Variable A/C Compressor Control Circuit incorporates multiple components to do the entire process. Newer vehicles come equipped with climate control, which is an important component for the circuit to work properly.

When the PCM (powertrain control module, also known as ECM or engine control module, and ECU or engine control module) detects an improper signal within the Variable A/C Compressor Control Circuit, then it activates the Error Code P06A0 and illuminates the Check Engine light.

Other related error codes include:

Common Symptoms

  • The AC (air conditioner) will not work properly

Possible Causes

There are many possible causes for this code, including:

  • Faulty A/C compressor
  • Faulty A/C solenoid (if applicable)
  • Clogged orifice tube or dryer
  • Low or overcharged system
  • Defective climate control
  • Faulty A/C relay
  • Blown fuse or fuse-able link (if applicable)
  • Corroded or damaged connector
  • Damaged or faulty wiring
  • Defective ECU

How to Check

As with most codes, the first step to diagnose this code is to check with the TSB (technical service bulletins) and look for the specific vehicle model, and power plant of the vehicle in question. This can save a lot of time in diagnosis for most circumstances.

Next, find all components within this circuit and perform a thorough visual inspection. Check the associated wirings and look for signs of damages, such as bare wires, rubbing, scraping, or burn spots. Then, check the connectors for security, damaged or corroded pins. The A/C compressor, and all associated sensors, such as relays and the ECU, must be included in the inspection process as well.

Advanced Steps

Advanced steps are vehicle specific, which require appropriate equipment, such as digital multi-meter and the specific technical references for the vehicle, as well as A/C diagnostic machine (if available).

This equipment can pinpoint the source of the malfunction by identifying leaks and verifying the right pressure within the system. High and low side gauges also validate the integrity of the A/C compressor and associated components. Any restrictions within this system, such as a clogged orifice tube or dryer, will be identified. The right amount of refrigerant in the system plays a significant role in the operation of the circuit as well. Safety switches, fuses, and fuse-able links are usually incorporated to prevent A/C compressor damage.

Voltage Checks

The specifics numbers and guidelines for voltage checks must be referenced from the TSB to determine the exact voltage ranges required for different A/C components. Based on the configuration, several components are incorporated, including the A/C compressor, relays, and solenoids for many applications. Some newer vehicles also come equipped with climate control, making troubleshooting process more complicated. Voltage requirements differ from model and year of the vehicle.

If this process confirms the lack of power source and ground, then you must conduct a continuity test to check the integrity of the connectors, wirings, and other components. Continuity test must be performed with the power removed from the circuit, and normal readings for wirings and connections must be at 0 ohms of resistance. Resistance or no continuity is an indication of faulty wiring, which could be caused by open or shorted wiring. This must be repaired, if not replaced, as soon as possible.

How to Fix

  • Replacement of A/C compressor
  • Replacement of A/C solenoid (if applicable)
  • Replacement of blown fuse or fuse-able link (if applicable)
  • Replacement of orifice tube or dryer
  • Repair of A/C system leak
  • Repair or replacement of fault in the wiring
  • Cleaning corrosion off of the connectors
  • Evacuate and recharge system
  • Flashing or replacement of ECU

Misdiagnosis may result in replacing the A/C compressor or other associated components when faulty wiring, connectors or an improper charge is the root of the problem.

Misdiagnosis of this problem can lead you to unnecessarily replace the A/C compressor or other associated components. Thus, make sure you check the connectors and wirings for an improper charge to identify the root of the problem.

The severity of this problem ranges from moderate to severe, depending on the specific nature of the problem. Malfunctions in the A/C can lead to extensive repairs when not addressed in a timely manner.