P2520 OBD Error Code: Problem & Solutions

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The trouble code P2520 can be defined as A/C Request 'A' Circuit Low. This error code would start indicating when the PCM has detected a voltage reading from a specific a/c refrigerant pressure sensor that would not fall within acceptable limitations. You can always consult the automobile service manual for the location of this particular sensor/switch.

The refrigerant pressure through the air conditioning (A/C) pressure sensor is being monitored by the engine control module. This trouble code would be set by the ECM when the signal from the sensor would not be as per the specifications set by the manufacturer. The engine control module, powertrain control module or the transmission control module monitors this circuit depending upon the particular automobile.

What causes this problem with the A/C Request 'A' Circuit Low?

• Less refrigerant
• There might be too much refrigerant
• Some flaws in the low side pressure sensor
• Low side pressure sensor harness might be opened or sometimes shorted
• Low side pressure sensor circuit might have inadequate electrical connection

1. Engine Control Module - There can be some engine performance issues due to faulty engine control module. If the ECM fails or has any problems it can lead to performance issues with the vehicle like misfires, hesitation, loss of power, and sometimes even decreased fuel economy.
2. A/C compressor - The AC compressor might not work properly due to rust, physical damage, oil leaks, or paint damage. Get it checked and replace if needed.
3. Powertrain Control Module - PCM stands for powertrain control module. It is a car part, a control unit which is utilized on motor vehicles. It is generally a combined control unit, consisting of the engine control unit (ECU) and the transmission control unit (TCU).
4. Electronic Control Unit - If your automobile's check engine light remains on constantly, and never goes off, there's a good chance that your vehicle has a damaged electronic control unit. There are a lot of reasons why a car's check engine light will remain on. The most common reason is a defective ECU.
5. Diagnostic Tools - It is always advisable to use the correct tools and equipment while resolving any OBD code issue as even small mistakes can lead to wrong diagnosis. Thus, always take help from a professional who has the knowledge and experience to such tools in an efficient manner. Buy new quality diagnostic tools from us today!

Our main motive is to achieve customer satisfaction as for us our customers are everything and that’s why we will help you to diagnose P2520 code by mentioning some major symptoms below:

Common Symptoms

• The service engine soon light can start lighting up
• Non functional air conditioning system
• The air conditioning system might be disabled
• The "ON" indicator lamp (generally in the a/c switch) might start flashing

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P2520:

• You must add refrigerant
• Make sure to mend the faulty wiring or connectors
• It is essential to restore the flawed A/C refrigerant pressure sensor
• Repair or replace the quirky high pressure switch
• Rehabilitate the leaks in the system
• Carefully adjust the faults in the A/C compressor switch 

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Here are some steps which you should follow in order to diagnose this fault code:

• This is a general type of error code which is diagnosed with the help of a scanner. The mechanic will insert a scanner to diagnostic port of the vehicle and recover the codes and freeze frame data. The average automotive AC system utilizes between one and four refrigerant pressure switches so that it can provide safe and efficient operation. Freon is utilized to distribute oil throughout the air conditioning system, so you can see that refrigerant pressure is crucial to a/c system longevity and operation. The pressure switches can be threaded onto metal a/c lines or inserted into the compressor.
• These switches are generally of a pressure sensitive "ON/OFF" design. Now as the pressure would rise in the a/c system it would press against spring tension in the low pressure switch. When sufficient pressure is reached for proper system operation, then the contacts which are inside of the switch would be closed and the compressor clutch electrical circuit is completed, thus it would allow the clutch to engage.
• The high pressure switches would operate in the same manner. When system pressure would become excessive, then it would press against spring tension inside the switch. When system pressure reaches a level that could be detrimental to the compressor and other major components, contacts inside the switch are opened and the electrical circuit for the a/c compressor is opened, which would cause the a/c clutch to disengage. Repeated failures (usually 3) of this nature are recorded by the powertrain control module.
• After a predetermined number of failure cycles would be completed, then this error code would be stored and there would be an illumination in the service engine soon lamp. Some models also disable the a/c compressor clutch until the code has been cleared. Several tools would be required to successfully diagnose this fault code. This is a general type of error code which is diagnosed with the help of a scanner. The mechanic will insert a scanner to diagnostic port of the vehicle and recover the codes and freeze frame data. If he happens to find any additional error codes, he has to address them as well. Once it is done, he has to reset the vehicle, and then test drive to see if the error code appears.
• If the error code does not return, then there can be an erratic condition. Then the mechanic has to check the wires, connectors and other electrical components and quickly replace them if he finds them to be damaged or defective. Make sure to retest the system after repairs are completed to ensure success. If all system wiring, connectors, and components appear to be in good working condition, connect the scanner (or code reader) to the diagnostic connector.
• Then the freeze frame data should be recorded. This information would be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored. You should continue by clearing the code and operating a vehicle to see if it returns.
• This will help to determine whether or not the malfunction is intermittent. Now once all the codes are cleared, then you should test drive the vehicle to see if the code returns. If the code fails to immediately return, then it is an indication that you have an intermittent condition. Intermittent conditions can prove to be quite challenging to diagnose and in extreme cases it should be allowed to worsen before a right diagnosis can be made.
• Connect the scanner or code reader and then record all stored trouble codes as well as freeze frame data. All the codes should be cleared up, then connect the a/c gauges, carefully start the car engine and then turn the a/c on high.
• The pressure gauge readings should be observed carefully. If the low pressure gauge reading drops below 29 psi, and compressor clutch engagement is disabled, suspect a low freon condition. Slowly add freon until the low pressure reading is approximately 35 psi (monitor high side pressure as well - it should maintain around 225 psi).
• If the compressor clutch is engaged and the a/c system begins to cool normally, check for leakage in the freon and then it should be repaired as per the requirement. If system pressure exceeds the manufacturer's minimum specifications (usually 30 psi) and the compressor clutch fails to engage, then it would indicate that there are some faults in the low refrigerant pressure sensor. Check for voltage and ground signals at the low pressure switch electrical connector.
• Compare your actual findings with manufacturer's specifications and repair open or shorted circuits as needed. If voltage and ground signals coincide with the specifications set by the manufacturer, then test the low pressure switch resistance utilizing the digital volt/ohmmeter. Compare your findings to the specifications set by the manufacturer and replace the switch as per the requirement. Then all the codes should be cleared up, connect the a/c gauges, start the engine and turn the a/c on high.
• The readings of the pressure gauge should be carefully observed. If the high pressure gauge reading exceeds the manufacturer's maximum specification (usually 275 to 300 psi), turn the a/c system off and the pressure should be allowed to decrease.
• Turn the a/c back on and observe the electric condenser fan (if so equipped) operation. If the electric cooling/condenser fan/s are not working, diagnose the cause of this issue. Lack of electric cooling/condenser fan operation will cause high pressure to soar. If the fan is working and a/c system pressure exceeds maximum recommended specs, suspect a restriction in the orifice, expansion valve, accumulator, receiver dryer, or condenser. If the high pressure reading is within specs and the compressor clutch fails to engage due to a high pressure condition, perform a resistance test on the high pressure switch and compare your findings with manufacturer's specifications.
• Restore the high pressure switch as required. If the switch does fall within acceptable specifications, examine continuity in the system circuit. Repair or replace defective electrical wiring and connectors as per the requirement. If a/c refrigerant pressure switches and circuitry fail to yield the cause of this malfunction, suspect a quirky climate control head or a/c compressor switch. Check the unit according to specifications set by the manufacturer and replace components as needed.

Common Mistakes When Diagnosing The P2520 Code

• Non performance of the A/C compressor
• Failure in the car wiring
• There might be a failure in the powertrain control module
• The A/C compressor relay might not function properly