Parts for your 2007 Nissan Serena-Tx valve

2007 Nissan Serena TX valve: what it does and when to service or replace it

Based on Nissan’s C25 Serena Electronic Service Manual (section HA – Heating & Air Conditioning), the Nissan FAST parts catalogue for C25, and DENSO’s OE A/C component listings, the 2007 Nissan Serena uses a thermostatic expansion valve (TX valve) for refrigerant control. Front A/C models have a TX valve at the front evaporator, dual A/C models (common on JDM/NZ imports) also have a rear TX valve at the rear evaporator. It’s not an orifice-tube system on this model year.

The TX valve meters liquid R‑134a into the evaporator and keeps a small, stable superheat, so the Serena’s cabin gets reliably cold without risking liquid slugging the compressor. On dual A/C Serenas, there’s a second TX valve doing the same job for the rear unit, helping passengers in the third row stay comfy on scorching summer runs.

While the TX valve isn’t a routine “replace-every-service” item, a bit of care goes a long way. If cabin cooling is weak at idle, the vents cycle hot–cold, the low-side line ices up, or pressures look erratic on gauges, the valve could be restricted or stuck. Contamination after a compressor failure can also foul the valve. When a TX valve is replaced, best practice per Nissan’s ESM is to renew the HNBR O‑rings (lightly oiled with the correct PAG oil), evacuate the system with a proper recovery unit, and charge by weight to the figure on the under‑bonnet label. On C25 cars, the receiver-drier is typically integrated in the condenser, so it’s smart to replace or service that component any time the system’s opened to air.

DIYers should note that handling refrigerant is regulated in Australia and New Zealand, an ARCtick/authorised tech should recover and recharge the gas. If the front dash TX valve is being replaced, expect some trim and HVAC case access, the rear unit is usually accessed at the rear quarter trim. Labour times vary with spec, but roughly:

• Front TX valve: about 1.5–3.0 hours
• Rear TX valve (dual A/C): about 1.0–2.0 hours

Good habits that help TX valves live a long life:

• Keep the cabin filter fresh to maintain airflow across the evaporator.
• Wash the condenser face so head pressures stay sensible.
• Use the correct oil type and quantity after any major A/C repair.
• If the system’s had a dirty failure, consider flushing lines and replacing both TX valves on dual A/C cars to avoid repeat issues.

Popular questions

Does the 2007 Serena have one or two TX valves?
Most 2007 Serena C25s with only front A/C have one TX valve at the front evaporator. Dual A/C models have two: one in the dash unit and a second near the rear evaporator in the rear quarter area. Many NZ‑import Serenas are dual A/C, so two TX valves is common.

What are the signs the TX valve is failing on a Serena?
Tell‑tales include poor cooling at idle, vent temps that swing hot and cold, frosting on the low‑side line or the evaporator case, and odd gauge readings (very low suction or hunting). After a compressor or drier issue, debris can clog the valve and mimic these symptoms.

Can a home mechanic replace the Serena’s TX valve?
The physical swap is straightforward for a capable DIYer, but refrigerant recovery and charging must be done by a licensed A/C tech in AU/NZ. If you’re pulling the valve, plan on new O‑rings, correct PAG oiling, vacuum dehydration, and a charge by weight. Many owners leave the whole job to an authorised technician.