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  1. How To
  2. FAQs: A/C Basics
  3. COMPRESSORS

In order to prepare a new compressor for installation, you will need to prime it. If you do not prime the compressor properly, you could seriously damage it and void the warranty on the product. Priming a compressor consists of adding oil to both the receiver/drier and the suction port of the compressor. Before starting, you will need to know the oil capacity of your system and your compressor. You can check here to get the system specs for your specific vehicle.

Once you have determined the proper amount of lubricant for your particular compressor, pour half of the amount specified into the suction port of the compressor and the other half of the specified amount into the receiver/drier.

Once you have installed the compressor back onto your car, you will need to rotate the compressor clutch 10–20 times to ensure that the oil is properly distributed throughout the system and the compressor. To do this, you will need a spanner wrench.

Do not turn the compressor nut in the middle of the pulley, as this may affect the air clearance between the clutch pulley and the clutch faceplate. After you have made 10–20 complete revolutions with the pulley, the compressor will be properly primed.

You can tell if your compressor is cycling on and off by looking at the clutch (or belt pulley) at the front of the compressor. The center of this clutch should be spinning when the compressor cycles on. Please note that the pulley itself will always spin while the center of the clutch may not.

If the compressor is engaging, the center of the compressor clutch will turn along with the outer pulley. If the pulley does not turn and there is a loud squeal, this usually indicates a locked-up compressor. The compressor and drier will need to be replaced. Here is a video showing a compressor that is running properly.

If the refrigerant charge is low, the low-pressure cutout or low-pressure cycling switch can prevent the clutch from engaging. Adding refrigerant should alleviate the problem.