2021 Chevrolet Silverado 3500HD A/C Refrigerant & Oil Capacity

Quick Answer

• Refrigerant Type: R-1234yf
• Full System Charge: 22 oz (624 grams)
• PAG Oil Type: PAG 46
• PAG Oil Amount: 6.0 oz (180 mL)
• Low-Side Service Port Location: On the suction line, typically near the firewall on the passenger side.
• High-Side Service Port Location: On the discharge line, typically near the condenser on the passenger side.

Why R-1234yf Matters

For your 2021 Chevrolet Silverado 3500HD, the A/C system uses R-1234yf refrigerant. This is a significant change from the older R-134a refrigerant, primarily driven by environmental regulations. R-1234yf has a much lower Global Warming Potential (GWP) compared to R-134a, making it more eco-friendly.

However, this transition comes with some implications:

• Cost: R-1234yf is significantly more expensive than R-134a, making repairs and recharges more costly.
• EPA Regulations: Due to its environmental impact, the EPA has mandated the use of R-1234yf in new vehicles since the 2021 model year (though many manufacturers started earlier). This means specialized equipment is required for handling this refrigerant.
• Recovery Machine Requirements: Servicing an R-1234yf system requires an EPA-certified R-1234yf recovery machine. Using equipment designed for R-134a can contaminate the system and lead to costly damage.

Recharge Procedure

Recharging your 2021 Silverado 3500HD A/C system is not as simple as just adding refrigerant until the pressure looks right. Proper technique is crucial for optimal performance and longevity of your A/C system.

1. Evacuation is Key: Before adding any new refrigerant, the system should be thoroughly evacuated using a vacuum pump. This process removes all air and moisture from the system, which can cause corrosion and hinder cooling performance if left unchecked. A deep vacuum (below 500 microns) is essential.
2. Charge by Weight, Not Pressure: Never rely solely on manifold gauge pressures to determine the correct charge. The only accurate way to charge an A/C system is by weight, using a precise refrigerant scale. Refer to the manufacturer