Parts for your 2002 Nissan Serena-Tx valve

2002 Nissan Serena TX Valve: What it does, where it lives, and how to look after it

Referencing technical sources, the 2002 Nissan Serena (C24) air-conditioning system is fitted with a thermostatic expansion valve (TXV). The Nissan Serena C24 Factory Service Manual (Heater & Air Conditioner/HA section: “Expansion Valve—Components, Removal and Installation”) details the TXV at the evaporator, and the Nissan FAST/ELCAT parts catalog lists front and rear expansion valves for C24 models equipped with dual (rear) A/C. Aftermarket catalogues from major A/C suppliers also list a direct-fit expansion valve for the 1999–2005 Serena/C24, further confirming TXV fitment.

The TX valve meters liquid refrigerant into the evaporator, using a sensing bulb to react to outlet temperature and pressure. On a Serena, that means steadier vent temps, better dehumidifying, and less chance of the evaporator icing up. If the vehicle has rear A/C, there’s a second TXV at the rear evaporator, so both ends can be controlled independently for family-hauler comfort.

When a TXV starts playing up, the signs are usually pretty clear: weak cooling at idle, frosty lines at the firewall, vent temps that swing hot–cold, or a system that cools on the motorway but not around town. A stuck-closed valve starves the evaporator, a stuck-open valve can flood it and wash heat out poorly. A proper diagnosis with manifold gauges and a temperature probe is the go-to before replacing parts.

Replacement isn’t difficult for a trained tech but does require correct procedure. The system must be recovered, the valve replaced with new O-rings (lightly oiled with the specified PAG oil), and the receiver–drier or desiccant bag renewed whenever the system’s been opened. Evacuate thoroughly to remove moisture, then recharge with the specified R134a charge weight and oil balance. On dual A/C Serenas, don’t forget the rear TXV—pressure readings and frost patterns can help pinpoint which circuit is the culprit.

Maintenance is mostly preventive: keep the condenser clean, run the air-con regularly to circulate oil, and service cabin filters so airflow across the evaporator stays strong. If metal debris is found anywhere in the system, flushing and a compressor health check are must-do items before fitting a fresh TXV, or the new valve can clog straight away.

• Common symptoms of a faulty TXV: uneven cooling, frost at the TXV/evaporator pipes, hissing that doesn’t settle, abnormal high/low pressures.
• Best practice: replace O-rings, renew the drier, vacuum properly, and recharge to spec, check for leaks with nitrogen and dye as needed.

Popular questions

Where is the TX valve on a 2002 Nissan Serena?
On front A/C systems, it’s mounted at the evaporator inlet, typically at the HVAC case behind the dash near the firewall area. Models with rear A/C have a second TXV at the rear evaporator assembly, usually tucked behind interior trim in the rear quarter area. Access varies by trim and seat layout.

How can someone tell if the TX valve is bad or the refrigerant is just low?
Low refrigerant usually shows low pressures on both sides and underwhelming cooling that worsens under load. A faulty TXV tends to create a mismatch—very low suction with normal/high head if restricted, or higher-than-normal suction if stuck open—plus frost near the valve. Proper gauge readings, line temperatures, and a leak test are the best way to differentiate.

Does the Serena use an orifice tube instead of a TX valve?
No. The C24 Serena platform is designed around a thermostatic expansion valve, and dual A/C variants use two TXVs. This is documented in the C24 service manual’s Heater & Air Conditioner section and reflected in OEM/aftermarket parts listings.