Do I Need to Add PAG Oil after Vacuum: Let’s Find It Out to Clear the Doubt

Do I Need to Add PAG Oil after Vacuum

The short answer to this question is yes. Suppose you’ve had to recharge your car’s air conditioning system after it lost refrigerant. 

In that case, you may also need to add more PAG oil. PAG oil is essential for proper lubrication of the AC compressor and lines. So when refrigerant leaks out, some of the PAG oil leaks out, too. 

Here’s what you need to know about adding PAG oil after vacuuming your AC system.

Reasons That The System Needs More PAG Oil

PAG oil (Polyalkylene Glycol) is a type of synthetic oil specifically designed for use in air conditioning systems. It mixes well with refrigerant and allows the compressor to run smoothly. 

PAG oil lubricates the internal components of the AC system, such as:

  • Compressor
  • Lines and hoses
  • O-rings and seals

Without enough lubrication, the compressor will wear out faster. Remember that, the oil also helps to prevent refrigerant leaks by keeping O-rings and seals conditioned.

Times That You Should Add More PAG Oil

Anytime you open up the AC system to perform a maintenance or some repairs, a little amount of PAG oil may escapes. Significant leaks that cause you to recharge the refrigerant will also lead you to lower oil levels. 

Here are some common scenarios that call for adding more PAG oil:

  • After evacuating and recharging the System due to leaks
  • Replacing major components like the compressor or condenser
  • Repairing leaks in AC lines or hoses
  • Flushing out old oil and debris after a compressor failure
  • Generally, you should add about 1-2 ounces of PAG oil for every pound of refrigerant added. Consult your vehicle repair manual for the specific amount recommended by the manufacturer.

The Drawback of Using Too Much of PAG Oil

Adding too much of PAG oil can actually hinder the air conditioning performances. 

Here are some potential issues:

  • Reduced cooling capacity
  • Blockages in small passages
  • Compressor damage from oil sludge
  • Leakage due to saturated seals

That’s why it’s essential to add the proper amount of oil based on refrigerant capacity. Remember that overfilling with PAG oil is just as problematic as being low on oil.

Importance of Vacuuming Before Recharging

  • You should always evacuate the AC system with a vacuum pump before recharging with a new refrigerant. 
  • This removes any moisture, contaminated oil, and non-condensable gases. 
  • Evacuating down to a deep vacuum ensures no trace gases remains that could reduce the cooling efficiency.

Types of PAG Oil That You Should Use

When adding PAG oil to your vehicle’s AC system, it’s essential to use the correct oil type recommended by the manufacturer. 

Here are some guidelines:

  • For older AC systems (pre-1990s), use mineral-based PAG oils like PAG 150.
  • For newer AC systems, use synthetic PAG oils like PAG 46 or PAG 100
  • Check your vehicle repair manual for the specific oil viscosity grade that is ideal.
  • Using the wrong PAG oil viscosity can damage the compressor. 
  • PAG 100 is the most common for modern cars. 
  • Make sure it’s specified for mobile AC use and not for any industrial systems. 
  • Remember to never mix PAGs of different oil grades in your system.

Frequently Asked Questions About Do I Need to Add PAG Oil after Vacuum

Q: Is PAG oil necessary for an electric car’s AC system?

A: Yes, electric vehicles still requires PAG oil to lubricate the compressor and seals even though they lack on engine-driven compressors.

Q: How do I know if the PAG oil level is low?

A: Symptoms of low oil are reduced cooling, strange noises from the compressor, refrigerant leaks, and clutch problems.

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