Parts for your 2003 Nissan Serena-Tx valve

2003 Nissan Serena TX Valve — fitment, purpose and service pointers

Based on the Nissan Serena C24 Factory Service Manual (Heating & Air Conditioning section), Nissan FAST electronic parts catalogue, and mainstream aftermarket catalogues (Denso, Nissens, Four Seasons), the 2003 Nissan Serena is equipped with a thermal expansion valve (TX valve). Front air-conditioning uses a TX valve at the evaporator, and models with rear A/C have a second TX valve at the rear evaporator. It’s not an orifice-tube system on this model year.

The TX valve’s job is to precisely meter refrigerant into the evaporator, using a temperature-sensing bulb to regulate superheat. That balancing act helps the Serena deliver consistently cold air at idle and on the open road, protects the compressor from liquid slugging, and keeps pressures where they should be for R134a. On dual A/C Seranas, each evaporator has its own valve so both the front and rear cabins cool efficiently.

Common signs the TX valve is struggling include slow or uneven cooling, vent temps that swing hot–cold, frosting or sweat on the evaporator lines, hissing at the dash, and pressure readings that are abnormally high or low even with the right refrigerant charge. Because the TX valve can stick or clog with debris or moisture, issues often show up after a leak or if the receiver–drier is overdue.

• Replacement pointers for a Serena: always recover the refrigerant first, then access the front TX valve at the evaporator housing (behind the glovebox), the rear valve sits with the rear evaporator assembly in the quarter/roof area on dual A/C models.
• Renew the O-rings, add the correct PAG oil amount for parts replaced, and fit a new receiver–drier whenever the system is opened.
• Flush contaminated lines (never the TX valve or compressor), evacuate for an appropriate time, verify the vacuum holds, and recharge by weight to the under‑bonnet spec label.
• Leak-check with nitrogen and/or UV dye, then confirm vent temps and pressure balance.

There’s no routine “service” for a TX valve beyond keeping the system healthy: change the cabin filter so airflow across the evaporator stays up, keep the condenser clean, and run the A/C regularly to circulate oil. If the Serena’s showing the symptoms above, a licensed A/C tech (ARCTick in AU or a certified handler in NZ) should test and, if required, replace the TX valve to restore crisp, reliable cooling.

Popular questions about 2003 Nissan Serena TX valve

Does the 2003 Serena use a TX valve or an orifice tube?
It uses a thermal expansion valve. Front systems have one TX valve at the evaporator, and dual A/C models add a second valve for the rear evaporator. This layout is documented in the C24 FSM and parts listings.

Where is the TX valve located on a 2003 Serena?
The front TX valve sits at the evaporator behind the glovebox area. On dual A/C versions, the rear TX valve mounts at the rear evaporator assembly, typically in the left rear quarter/roof ducting behind interior trim.

Can a TX valve be replaced without evacuating the refrigerant?
No. The system must be professionally recovered and evacuated before opening the circuit. After replacement, renew O-rings, fit a new receiver–drier, perform a vacuum and leak test, and recharge by weight with R134a.