2018 Ram 3500 A/C Refrigerant and Oil Guide

Quick Answer: 2018 Ram 3500 A/C Specifications

• Refrigerant Type: R-1234yf
• Refrigerant Charge Capacity: 23.0 oz (652 g)
• PAG Oil Type: PAG 46 (SP-A2)
• PAG Oil Capacity (Full System): 5.1 oz (150 mL)
• Low-Side Port Location: Near the firewall on the passenger side, on the larger diameter A/C line.
• High-Side Port Location: In front of the passenger side shock tower, on the smaller diameter A/C line.

Disclaimer: A/C service can be hazardous. Always wear safety glasses. Handling refrigerants requires EPA Section 609 certification in the United States. Improper service can lead to system damage or personal injury. When in doubt, consult a professional.

Why R-1234yf Matters

Starting in the mid-2010s, automakers began transitioning from R-134a to the more environmentally friendly R-1234yf refrigerant. Your 2018 Ram 3500 uses R-1234yf, which has a much lower Global Warming Potential (GWP) than its predecessor. While this is great for the atmosphere, it comes with a few considerations for the vehicle owner:

• Cost: R-1234yf refrigerant is significantly more expensive per pound than R-134a.
• Service Equipment: Servicing R-1234yf systems requires dedicated, specialized A/C recovery and charging machines to prevent cross-contamination. Shops have made significant investments in this new equipment.
• Flammability: R-1234yf is mildly flammable, which is another reason why specific service procedures and equipment are necessary.

A/C Recharge Procedure Overview

Topping off an A/C system with a can from the auto parts store is not the correct way to service your Ram's A/C. Modern systems are highly sensitive to the exact amount of refrigerant and oil. The only proper method is to charge by weight.

A professional service involves these key steps:

1. Recovery: All existing refrigerant is recovered from the system using an EPA-approved machine.
2. Evacuation: The system is placed under a deep vacuum for at least 30-45 minutes. This removes all air and moisture, which are enemies of A/C performance and longevity. If the system cannot hold a vacuum, there is a leak that must be repaired.
3. Recharging: The exact factory-specified weight of R-1234yf (23.0 oz) is injected back into the system, along with the correct amount of PAG 46 oil if any components were replaced.

Charging based on gauge pressures alone is inaccurate and can lead to poor cooling, component damage, and compressor failure.

Common A/C Problems for This Generation Ram

While generally robust, the A/C systems on heavy-duty Rams can experience a few common issues:

• Condenser Leaks: Located at the very front of the truck, the condenser is vulnerable to damage from road debris like rocks and stones. A small puncture can lead to a complete loss of refrigerant.
• Compressor Failure: The A/C compressor is the heart of the system. Clutch failures or internal mechanical failures can occur, often spreading debris throughout the entire system. A proper repair requires replacing the compressor, condenser, and expansion valve, and thoroughly flushing the lines and evaporator.
• Evaporator Core Leaks: Though less common, leaks can develop in the evaporator core, which is located inside the dashboard. This is a labor-intensive repair that requires removing the entire dash assembly. A tell-tale sign can be a musty smell from the vents or an oily residue on the inside of the windshield.

When to Call a Pro

While some DIY maintenance is straightforward, A/C system service is best left to certified professionals. If you're experiencing poor cooling, strange noises from under the hood when the A/C is on, or if your system is completely dead, it's time to have it diagnosed.

A professional shop has the diagnostic tools, specialized R-1234yf service equipment, and the EPA certification required to do the job safely and correctly.

Need an expert? Find a certified A/C shop on Repairius.