Monthly Archives: July 2025

If you need to add refrigerant to your air conditioning system, it’s a good idea to add or replace A/C compressor oil at the same time. A/C compressors are designed with a pulley assembly that allows it to engage and disengage with the clutch, and this cycling can cause lots of stress. With this guide, you’ll learn how to safely evacuate the A/C system and add oil to your compressor.

WHAT YOU’LL NEED:

• Air conditioning reclaimer with gauges
• Sockets
• Ratchet
• Wrenches
• A/C compressor oil (NOTE: do not use refrigerant/oil combos, as these will harm your system)

How to Add Oil to Your Auto’s A/C Compressor

Before adding oil, you need to evacuate the A/C system with a recovery machine or reclaimer. Failing to do so will cause refrigerant to be released into the atmosphere, which is illegal in North America. To do this, hook the red valve on the front of the reclaimer to the high side (small diameter) valve on the A/C unit, and hook the blue valve to the low side (large diameter valve). Turn the machine on, open the charging tank and reclaimer valves, and let it run until both gauges read “0”. Turn the valves off and disconnect the lines.

Next, use your sockets and wrenches to remove the electrical connector, drive belts, manifold lines, and finally the compressor. Hold the open end down and rotate the clutch by hand to empty the existing oil. Pour new oil very slowly into the intake port, while slowly rotating the hub and clutch. (You can get the correct oil amount from the A/C sticker on your vehicle or from your vehicle manual). Let the compressor sit for 10 minutes to allow the oil to soak into the front seals, then reinstall the compressor and unit parts.

To restore the refrigerant, reattach the reclaimer hoses, open the valves and run it in “vacuum” mode for 30 minutes. When this is done, run the “charge” mode until all the refrigerant has been pushed back into the system (the reclaimer will indicate when this is done). Remove the reclaimer lines and reinstall the valve caps.

You can read more about replacing your auto’s A/C refrigerant here.