2018 Ford F-350 Super Duty — A/C Refrigerant & Oil Capacity

Quick answer

• Refrigerant: Most 2018 Ford F-350 Super Duty models use R-134a (Ford’s heavy-duty trucks stayed on R-134a longer than many light-duty models during the 2014+ transition). A small number of late-production/fleet builds may use R-1234yf—always confirm the underhood A/C label.
• Full system charge: Most common spec ~30.0 oz (≈850 g) of R-134a. Exact charge can vary slightly by cab/climate package; verify the label under the hood for your VIN.
• PAG oil: PAG 46 (Motorcraft equivalent commonly sold as YN-12c). Total system oil is typically ~7.0 oz (≈207 mL). Add only the specified portion when replacing individual components per Ford service procedures.
• Service ports:
  • Low side: On the suction line near the accumulator/receiver at the passenger-side firewall area.
  • High side: On the liquid line near the condenser at the front/passenger side of the radiator support.

Why R-1234yf matters

Many 2014+ vehicles transitioned from R-134a to the lower-GWP refrigerant R-1234yf. While most 2018 Super Duty trucks still use R-134a, always read the A/C label before charging—charging the wrong refrigerant is expensive to correct and can damage the system. Key differences:

• Cost: R-1234yf is significantly more expensive per ounce than R-134a.
• Equipment: R-1234yf requires dedicated, SAE J2843–compliant recovery/recycle/recharge machines and unique service couplers; it must not be mixed with R-134a.
• Compliance: The EPA and automakers require refrigerant identification and proper recovery. Shops must maintain separate machines, hoses, and oil for yf systems to avoid cross-contamination.

Recharge procedure (high-level)

• Identify the refrigerant: Read the underhood label to confirm R-134a vs. R-1234yf and the exact factory-specified charge.
• Inspect first: Look for oily residue at fittings, condenser, and hose crimps. Repair leaks before charging—topping off a leaking system is not a fix.
• Recover any remaining refrigerant: Use certified equipment to capture and measure what’s in the system. Never vent refrigerant.
• Evacuate: After leak repairs, connect a vacuum pump through a micron-rated setup and pull a deep vacuum (≈30 inHg) for 30–45 minutes, then verify it holds. Moisture and air reduce cooling and can damage the compressor.
• Charge by weight: Charge the exact amount on the label using a calibrated scale. Do not charge “by pressure” or “until it feels cold.” Modern variable-displacement compressors and expansion devices require the correct mass of refrigerant.
• Oil balancing: If you replaced components, add the Ford-specified amount of PAG 46 for that component (for example, compressor, condenser, evaporator, or accumulator) so the total system oil stays near ~7.0 oz/207 mL. Use only OEM-approved oil; avoid universal dyes/oils unless specified.

Common A/C problems for this generation

• Condenser damage/leaks: The front-mounted condenser is exposed to road debris; stone impacts can create slow leaks. Look for oily dirt streaks on the condenser fins.
• Compressor control valve issues: Variable-displacement compressors may exhibit poor cooling at idle or fluctuating vent temps when the control valve sticks or when charge is slightly low.
• Orifice tube/expansion device contamination: Debris can clog the metering device, causing low cooling performance and abnormal pressure readings. Inspect the orifice screen if the system has been open or a compressor has failed.
• Evaporator or line leaks: Cabin odors with oily film at the drain, or dye traces at line joints, can indicate leaks. Use nitrogen/trace gas and an electronic leak detector for confirmation.
• HVAC door actuators: Not a refrigerant-side fault, but failed blend/temperature door actuators can mimic A/C problems by mixing in hot air.

OEM service info

• Always prioritize the exact specifications on your vehicle’s A/C identification label (charge weight and refrigerant type) and reference the Ford service manual for procedures, torque specs, and oil distribution per component.
• Ford commonly specifies PAG 46 oil (Motorcraft YN-12c) for Super Duty models in this era, with a total system oil volume around 7.0 oz (207 mL). Component replacement oil amounts vary by part and must be followed per the manual to avoid over- or under-oiling.

When to call a pro

• Your system won’t hold vacuum, pressures are abnormal, or cooling is intermittent.
• Refrigerant identification shows contamination or the wrong refrigerant.
• You’re working with R-1234yf (requires dedicated machines and procedures).

Safety disclaimer: Servicing mobile A/C systems requires EPA Section 609 certification. Use the correct refrigerant and oil, recover rather than vent, and follow all OEM and EPA/SAE procedures.

Find a certified A/C shop on Repairius.