Air Conditioner Compressor Replacement

Easy to follow step by step instructions on how to replace an automotive air conditioner compressor, though appearances may differ, the process is the same on most vehicles.

Difficulty Scale: 5 of 10

Before work begins, park the vehicle on a flat surface, with the emergency brake on, engine "OFF", use a basic set of tools while wearing protective eyewear and gloves.

Tools and Supplies Needed

  • Air Conditioner Compressor
  • Compressor oil
  • Typical tool set
  • Shop towels
  • Safety eyewear
  • Gloves
Air conditioner systems deal with refrigerant under high pressure so use caution.

NOTE: If the system is "flat" and all refrigerant has escaped, continue with this guide, if the system is full visit - How to vacuum down and recharge an A/C system

Step 1 - Remove the negative cable from the battery. (Note: Before disconnecting the battery, record radio presets, they will need to be re-entered after the battery is reconnected.) Learn more

Remove Negative Battery Cable

Step 2 - Unbolt and remove any tubing or hoses to gain access to the serpentine belt and compressor.

Remove Tubing

Step 3 - Using a wrench, release tension on the serpentine belt and remove it. Learn more

Remove Serpentine Belt

Step 4 - To gain access to the compressor, an accessory such as an alternator may need to be removed. Learn more

Remove Accessory Mounting Bolts

Step 5 - Removing these obstacles will allow room for the compressor to be removed.

Remove Accessories

Step 6 - Find the low side pressure port which is on the larger of the two refrigerant tubes and remove the cap, this will be used to recover the refrigerant from the system. (locations will vary). Learn more

Low Side Pressure Service Port

Step 7 - Using a small pick or screwdriver release electrical connector safety to remove the connection from the compressor, there may be more than one wiring harness connector on some models. (Note: On some models this step may need to be performed after the compressor mounting bolts have been removed.)

Remove Electrical Connector

Step 8 - Once all refrigerant has been released or recovered and pressure readings are at zero, locate and remove high and low side compressor lines mounting bolts. (Note: On some models this step may need to be performed after the compressor mounting bolts have been removed.)

Remove Compressor Refrigerant Lines

Step 9 - Firmly grasp the line bulkhead and pull up to disconnect, there is an O ring seal which can make a tight fit, a small amount of refrigerant (pressure) maybe released as well, complete this step by removing the low side fitting.

High Side Line Removed

Step 10 - Once all wiring harness connectors and refrigerant lines have been removed, locate and remove lower compressor mounting bolts.

Remove Compressor Mounting Bolts

Step 11 - While removing the last mounting bolt, grasp the compressor and remove it from the engine bay.

Remove Air Conditioner Compressor

Step 12 - Once the compressor has been removed, turn the compressor pulley or clutch to determine its condition by checking for a rough or grinding noises, this sometimes means the system is contaminated with foreign debris from the failed compressor which can plug an orifice tube or expansion valve. In sever cases the system must be flushed and the valve or orifice tube replaced, along with the receiver dryer or accumulator. Inspect for obvious contamination by checking refrigerant lines or compressor ports for problems, the system should only contain a slight amount of compressor oil.

Rotate Compressor

Step 13 - Compare the new compressor to the old unit to ensure a proper installation. (Note: Slight design appearance variations may be present).

New Air Conditioner Compressor

Step 14 - Transfer any mounting bolts or hardware before reinstalling the new compressor, in some cases it helps to leave the mounting bolts in the compressor for easy installation. 

Transferring Bolts and Hardware

Step 15 - Though the system has peg oil throughout its internal workings including the compressor, its a good idea to add a couple of ounces of compressor oil to ensure proper lubrication before installation, reinstall dust caps. (Note: Some compressors have oil already installed.)

Adding Compressor Oil

Step 16 - O rings are used to seal the high and low side lines to the compressor.

O Ring Seal

Step 17 - Using a small screwdriver or pick, carefully remove the O ring seal.

Remove O Ring Seal

Step 18 - Match the old O ring to the new unit to ensure proper a seal.

O Ring Seal

Step 19 - After cleaning the fitting thoroughly install the new O ring seal, once installed apply a thin layer of compressor oil over the seal to easy installation, repeat this process for each line.

Install O Ring Seal

Step 20 - Clear any hoses or lines while gently lowering the new compressor into the engine bay, hand thread the mounting bolts.

Install New Compressor

Step 21 - Use a wrench or socket to tighten the mounting bolts evenly.

Tightening Compressor Bolts

Step 22 - Remove the dust covers and install both compressor lines, then the mounting bolts and tighten.

Tighten Line Bolt

Step 23 - Both refrigerant lines installed using new O ring seals.

Refrigerant Lines Installed

Step 24 - Keep the electrical connector clean and dry before reconnecting it to the compressor.

Reconnect Electrical Connector

Step 25 - Reinstall any accessories such as the alternator by gently lowering the unit into the engine bay while installing the mounting bolts and electrical connectors.

Reinstall Alternator

Step 26 - While releasing the belt tensioner, reinstall the serpentine belt, recheck to make sure all pulleys are properly seated.

Reinstall Serpentine Belt

Step 27 - Reinstall and tighten any bolts, screws, clips or brackets removed in the process.

Reinstall Bolt

Step 28 - Before re-charging, the system must be evacuated, to re-charge an AC system please VISIT - Air Conditioner Recharge

Helpful Information

An air conditioner compressor can fail either by leakage or by internal mechanical problems which is usually accompanied by abnormal noises while in operation. If the air conditioner is weak or not working visit - Air Conditioner Not Working

Best Practices

  • Use refrigerant leak detector to make sure no refrigerant leaks are present.


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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