Parts for your 2015 Nissan Serena-Tx valve

2015 Nissan Serena TX Valve — What It Does and When to Replace It

Based on technical documentation, the 2015 Nissan Serena (C26 series) uses a thermostatic expansion valve (TXV) in its air-conditioning system. The Nissan Electronic Service Manual for C26, Heater & Air Conditioning (HAC) section, depicts an expansion valve fitted at the front evaporator, and models with rear A/C include a second TXV at the rear unit. Nissan’s FAST parts catalogue lists an expansion valve assembly for C26 Serena variants, and major aftermarket catalogues from DENSO and Nissens supply direct-fit TX valves for 2010–2016 Serena models. These sources confirm the TXV is the metering device used on this vehicle.

The TX valve is the metering heart of the Serena’s A/C, regulating how much liquid refrigerant enters the evaporator. By responding to evaporator outlet temperature and pressure, it keeps superheat in the sweet spot so occupants get steady, cold air without freezing the core. On Serena grades with rear air, there’s a second valve doing the same job for the back cabin.

When it’s time for servicing, a tired or contaminated TXV can show up as weak cooling at idle, big swings between cold and warm air, frosting at the evaporator pipes, or pressure readings that don’t stack up. Because TXV issues often come from moisture or debris in the system, a proper repair isn’t just swapping the valve — it’s clean, methodical A/C work.

• Always recover the refrigerant, don’t vent it.
• Replace O-rings, lubricate with the correct PAG oil, and torque fittings to spec.
• If the system’s been open or the compressor’s had a bad day, flush lines where appropriate and renew the receiver–drier/desiccant (on many Serenas it’s integrated with the condenser).
• Evacuate with a vacuum pump to remove air and moisture, then recharge with the specified R134a mass for the vehicle configuration (front-only vs dual A/C differ).

Access to the front TXV is at the HVAC case near the evaporator (behind the dash area), while the rear unit sits by the rear evaporator assembly in the quarter trim on dual-A/C models. There’s no calibration step for the valve itself, but it pays to clear HVAC self-diagnosis codes if present and always refit the cabin filter — a clogged filter can contribute to icing and poor airflow, which mimics TXV faults.

For owners chasing reliable, chilly air on summer road trips, having an A/C specialist pressure-test, leak-check, and assess the TXV condition during routine servicing keeps the Serena feeling fresh without blowing the budget.

Popular questions about the 2015 Nissan Serena TX valve

Where is the TX valve located on a 2015 Serena?
On front A/C systems, it’s mounted at the evaporator inlet within the HVAC case behind the dash, accessible after removing trim and the evaporator connections. Dual A/C models add a second TX valve on the rear evaporator in the left rear quarter area behind interior panels.

What are common symptoms of a failing TX valve on a Serena?
Expect inconsistent cooling, warm air at idle, frosting on the evaporator pipes, audible hissing at the valve, or pressure readings showing very high high-side and very low low-side. These can also be caused by low charge or a weak compressor, so gauge testing helps pinpoint the culprit.

Should both TX valves be replaced on dual A/C Serenas?
Not always. If diagnostics isolate the fault to the front or rear circuit, replace the affected valve. If there’s contamination (metal, sludge, moisture), replacing both TXVs, flushing lines, renewing the desiccant, and verifying oil balance is the smarter long-term fix.