Nissens 999938 A/C Expansion Valve - Front

Nissens A/C Expansion Valve for Mercedes-Benz

The Nissens 999938 thermal expansion valve is a block-style A/C flow restrictor built for precise refrigerant control in Mercedes-Benz HVAC systems. It is made from aluminum and uses R134 refrigerant, with OE-style sealing and mounting support where applicable.

Key Features

• Block-style A/C expansion valve for controlled refrigerant metering
• Aluminum construction for HVAC system durability
• Designed for R134 refrigerant systems
• Includes O-rings and mounting hardware
• OE-matching pressure performance, tightness, opening, set-point setting, and internal finish
• Part number 999938 for accurate ordering and service matching

Product Details

Nissens thermal expansion valves are manufactured to strict quality standards and validated for pressure performance, sealing integrity, opening behavior, set-point accuracy, and internal finish. This helps maintain proper refrigerant flow through the evaporator circuit and supports stable cabin cooling performance. The 999938 expansion valve is a direct-fit service part for select Mercedes-Benz GLE, GLS, GL, and ML models, including applications such as the 2016-2019 Mercedes-Benz GLE350, 2018-2019 Mercedes-Benz GLS450, and 2012-2015 Mercedes-Benz ML350. This part cross-references UAC EX10550C for the same application.

Common Issues It May Address

• Weak or inconsistent A/C cooling output
• Improper refrigerant metering at the evaporator
• HVAC performance problems caused by a worn expansion valve
• Sealing issues related to aged valve O-rings
• Service replacement needs on Mercedes-Benz GLE, GLS, GL, and ML A/C systems

Installation Notes and Tips

• Verify the vehicle uses an R134 refrigerant system before installation.
• Confirm the correct fitment by year, model, and position before service.
• Replace sealing components during A/C service and inspect mating surfaces for contamination or damage.
• Evacuate and recharge the system according to factory service procedures after installation.
• For fitment-specific applications, this part fits 2016-2019 Mercedes-Benz GLE350, 2018-2019 Mercedes-Benz GLS450, and 2012-2015 Mercedes-Benz ML350, among other listed Mercedes-Benz models.

Quality Assurance

Nissens validates each expansion valve for pressure control, tightness, opening characteristics, set-point accuracy, and internal finish to align with OE matching standards. The 999938 is built to support consistent HVAC service quality on Mercedes-Benz applications.