How to Replace an AC Compressor

how to replace an ac compressorAir conditioning has not always been a standard item on an automobile.  The first air conditioning system wasn’t available in a car until the 1930s.  Air conditioning systems weren’t widely purchased in cars until the 1970s where the option was sold on more than half of the cars sold in the US, in large part due to low resale values of non-ac equipped cars.  Today, it’s hard to imagine finding a car that doesn’t have air conditioning.  Most cars today that don’t have air condition came factory equipped with it, but the system has gone into disrepair and may not have worked for a long time.

Perhaps this is the case with your vehicle, and an old and unused AC compressor has seized up and left you sweating.  Or maybe for you a recent test of your air conditioning system to get you ready for summer has shown you have a low pressure on the high pressure side of your compressor making your system barely work.  In some cases the clutch can fail on your AC compressor so the pulley cannot transfer the power to the compressor.  These are the most common causes of a failed AC compressor, but in all the cases they will require the replacement of the compressor.

If you’re ready to learn how to replace an AC compressor, read this whole article first before you head to the garage.  Replacing an AC compressor is almost as simple as replacing any other accessory on your motor like the alternator or power steering pump.  The biggest difference is that before you remove the actual compressor you have to remove the refrigerant lines connect to it.  There should be 2 lines, a high pressure and a low pressure line.  Before you can remove these lines, you first have to remove all the refrigerant from the system.  The low pressure side of your system could be from 30-60 psi and your high pressure side up to 200 psi.  With all that pressure in the system, simply removing the lines full of refrigerant at those pressures can be very dangerous.  To remove the lines from your AC compressor you should first have the system safely evacuated of refrigerant.  Once the system is empty, removing the lines is as simple as removing a few bolts.

With the lines off, you can move onto removing the compressor so you can replace it.  Start by removing the belt connecting the AC compressor pulley to the crankshaft pulley.  This may be done by releasing a belt tensioner or backing down on the adjusting screw for the AC compressor or its idler pulley.  Once you have the belt off, removing the AC compressor is as simple as removing the mounting bolts holding it the engine block or brackets.

After you’ve got the new compressor bolted in, you can replace the belt, and low and high pressure lines.  When reinstalling the lines you should consider installing new O-rings on the lines to make sure you have a good fit and no leaks.  If your AC system is old enough to need a new compressor, chances are you may have a few leaks in other places like the connection of rubber hoses to hard lines, the condenser and other connections.  After you install your new compressor you will have to refill your system with refrigerant, and if there are leaks, you will slowly lose that refrigerant causing your system to malfunction again.

After you’ve installed your new compressor consider adding BlueDevil Red Angel A/C Stop Leak to your system before it is refilled with refrigerant.  BlueDevil Red Angel A/C Stop Leak will remain inert in your system without damaging your new compressor or any other part of your system.  When it reaches a leak point, it will quickly seal the leak by forming a chemical weld.  This will help keep the new refrigerant in your system, and your new compressor working properly.

Red Angel AC Stop Leak & Conditioner

For more information about BlueDevil Red Angel A/C Stop Leak, visit our information page here: AC Stop Leak Aerosol

After you’ve replaced your compressor you can stop by any of our partnering auto parts retailers to purchase any BlueDevil products:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributor
  • DYK Automotive


Pictures provided by:

air_conditioning.jpg – By n23club – Licensed by Creative Commons via Pixabay – Original Link

Related Posts

3 responses to “How to Replace an AC Compressor

  1. You make a good point about checking the rubber hoses on your AC unit before filling your new compressor with refrigerant. That way, you do not risk losing compression and refrigerant through small leaks in the hoses. Many of these things can be avoided by hiring an experienced professional to do the work. Doing so, you will avoid these types of issues and other things you might not be aware of during installation.

    1. Neal,

      Thanks for your question about your AC compressor. You do not need to fill the new compressor before you install it, but you should install new refrigerant and oil before you start the system. The refrigerant your system uses is a gas when it is installed so it will fill the system naturally.

      Thanks again for your question!
      -BD Auto Pro

Leave a Reply

Your email address will not be published. Required fields are marked *