Range Rover P38 compressor won’t run: symptoms and fixing it

As an experienced Range Rover owner and mechanic, I know firsthand the reliability issues that come with owning this luxury vehicle.

But when the compressor won’t run on my Range Rover P38, even I’m stumped. If you’re facing the same issue, don’t worry, I’ve got you covered.

What models are affected?

Signs and symptoms

When the compressor won’t run on your Range Rover P38, you’ll notice a lack of air conditioning and poorly functioning front and rear suspensions.

Additionally, you might hear a grinding noise coming from the engine bay.

List of possible OBD codes

Depending on the specific cause of the issue, you might receive the following OBD codes:

  • P1484- Electric Fan Circuit Fault
  • P1485– Electric Fan Fault
  • P0733- Gear Ratio Error in 3rd gear
  • P0734- Gear Ratio Error in 4th gear

Common causes

There are a few common causes for a Range Rover P38 compressor that won’t run:

  • Faulty Relay: The compressor relay can get stuck or burn out, preventing the compressor from starting.
  • Failed Compressor: Over time, the compressor can fail due to wear and tear or refrigerant leaks.
  • Blown Fuse: A blown fuse can cause a range of electrical issues, including the compressor not starting.
  • Low Refrigerant: Low refrigerant levels can cause the compressor to shut off automatically in order to avoid damage.
  • Faulty Pressure Switch: A bad pressure switch can prevent the compressor from turning on.

Can it be fixed without a mechanic?

Some of the issues causing the compressor to not run can be fixed without the help of a mechanic. However, depending on the specific cause, a visit to the mechanic may be necessary.

Parts you’ll need to fix it

If you’re attempting to fix the issue yourself, you’ll need the following parts:

  • Compressor relay
  • New compressor (if the compressor is the issue)
  • Replacement fuse (if blown)
  • Refrigerant refill kit
  • Pressure switch (if faulty)

Tools you’ll need to fix it

In order to troubleshoot and fix the compressor, you’ll need the following tools:

  • Pressure gauge
  • Screwdriver
  • Wrench set
  • Repair manual
  • Refrigerant gauge
  • Digital Multimeter

How to fix it

Follow these steps to troubleshoot and fix the compressor:

  1. Check the compressor relay and replace it if necessary.
  2. Test the compressor with a multimeter to ensure that it’s receiving the proper voltage.
  3. Check for refrigerant leaks and refill if necessary.
  4. Replace the compressor if it has failed and is not functioning.
  5. Replace the pressure switch if it’s faulty.
  6. Check the fuse and replace it if necessary.
  7. Test the electrical connections and fix any loose or corroded wires.

Potential alternative causes

If the above fixes do not solve the issue, it’s possible that there’s a problem with the main unit or wiring harness connections. In this case, a mechanic will need to diagnose and fix the issue.


What if the compressor still won’t turn on after replacing the relay?

If the compressor still won’t turn on after replacing the relay, check the wiring connections and makes sure that there is power to the relay. If everything checks out, it’s possible that there’s a problem with the compressor unit itself.

Why is my air conditioning not working even though the compressor is turning on?

If the compressor is functioning but your air conditioning still isn’t working, you might have a problem with the blend air doors in your Range Rover. These doors might be stuck or malfunctioning, preventing cool air from flowing through the vents.

Can I continue driving my Range Rover if the compressor won’t run?

It’s not recommended to continue driving your Range Rover if the compressor won’t run. Not only will you be without air conditioning, but the poorly functioning suspensions can cause damage to your vehicle over time.


Dealing with a Range Rover P38 compressor that won’t run can be frustrating, but with the right knowledge and tools, you can troubleshoot and fix the issue.

Don’t hesitate to seek the help of a mechanic if needed, as there could be more complex issues at play.

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