Parts for your 2005 Nissan Pathfinder-Tx valve

2005 Nissan Pathfinder TX Valve: what it does and when to replace it

Based on the Nissan Pathfinder R51 (2005) Factory Service Manual – HA (Heating & Air Conditioning) section – and the Nissan Electronic Parts Catalogue (FAST), the 2005 Pathfinder runs a thermostatic expansion valve (TX valve, or TXV) on the A/C system. Front A/C models use a single TX valve at the evaporator, models optioned with rear air have a second TX valve for the rear evaporator. This layout is consistent with DENSO/Nissan HVAC designs of the era, which specify a TXV rather than a fixed orifice tube to regulate refrigerant flow.

On this Pathfinder, the TX valve meters liquid R134a into the evaporator based on evaporator outlet temperature/pressure, keeping superheat in the sweet spot. That means colder vents at idle, better control during stop–go traffic, and less chance of the evaporator icing up. It’s a precision bit of gear that does the thinking so the rest of the system doesn’t have to work as hard.

For front A/C, the TX valve sits at the evaporator inlet in the HVAC case (accessed from the passenger side/behind the glove box). If equipped with rear air, a second valve lives with the rear evaporator in the rear quarter trim. When one sticks or clogs, you’ll typically see poor cooling at idle, vent temps that swing hot–cold, frost on the evaporator pipe, or high/low side pressures that don’t track as they should under load.

There’s not really “maintenance” for a TX valve, but good servicing habits go a long way:

• Keep the cabin filter fresh to stop debris building up on the evaporator core.
• Fix any refrigerant leaks promptly, moisture and muck in the circuit can foul the valve.
• At any major A/C repair, replace the receiver–drier (or condenser desiccant bag, depending on build) and the O-rings you disturb.

Replacing a TX valve on a 2005 Pathfinder is a straightforward job for a licensed air‑con tech: properly recover the refrigerant, remove the evaporator access, swap the valve and O‑rings, evacuate, then recharge by mass to the under‑bonnet label (front‑only systems typically use less gas than rear‑A/C models). While in there, the tech will check the evaporator for contamination and verify superheat and vent temps on completion. DIY gassing is a no‑go in Aus/NZ, always use a licensed professional.

If the A/C is still cooling but not brilliantly, a performance test can confirm whether the TX valve is the culprit or if you’re simply low on charge. A solid service with leak detection, fresh drier, and the correct charge often restores the Pathfinder’s chilly demeanour without further drama.

• Does a 2005 Nissan Pathfinder have a TX valve or an orifice tube?
  Yes, it uses a thermostatic expansion valve. This is documented in the Nissan R51 Factory Service Manual (HA section) and shown in the Nissan FAST parts catalogue. Rear‑A/C models have a second TX valve at the rear evaporator.
• Where is the TX valve located on a 2005 Pathfinder and how long to replace?
  The front TX valve is at the evaporator inlet behind the glove box area, the rear valve (if fitted) is in the rear quarter trim. A trained tech typically allows around 1.5–3 hours for the front, more if dealing with rear trim and lines.
• Should the TX valve be replaced as preventative maintenance?
  Not usually. It’s replaced when faulty or when the system has suffered contamination. Focus on keeping the system clean, leak‑free, and correctly charged.