Parts for your 2000 Nissan Pathfinder-Tx valve

2000 Nissan Pathfinder TX Valve — Fitment, purpose and practical servicing advice

Based on technical references, the 2000 Nissan Pathfinder (R50) is fitted with a thermal expansion valve (TXV) at the evaporator, not an orifice tube. The Nissan Factory Service Manual for the 2000 Pathfinder (HA: Heating & Air Conditioning), Nissan parts catalogues under the Expansion Valve group, and major aftermarket catalogues (DENSO and Four Seasons) all list a direct-fit TXV for this model, confirming its relevance and use.

The TX valve’s job is to meter the flow of R134a into the evaporator so the core runs cold without icing up. It reacts to evaporator outlet conditions via an internal diaphragm and spring, balancing superheat so the compressor isn’t fed liquid. When it’s working right, the cabin gets quick, steady cool-down with stable vent temps—ideal for Aussie and Kiwi summers.

On the 2000 Pathfinder, the TXV is mounted at the evaporator inlet (at the firewall/evaporator case interface). Access is typically via the passenger side area and the engine bay where the A/C lines pass through the bulkhead. Common symptoms of a crook TXV include: weak cooling at idle, random hot–cold swings, frosting on the suction line, compressor short cycling, or pressure readings showing a starved or flooded evaporator.

Replacement is a professional job. Because refrigerant must be recovered, an ARCtick-authorised technician should handle it. A sound service approach looks like this:

• Recover refrigerant, disconnect lines, cap openings to keep moisture out.
• Replace the TXV and all related O-rings, lightly oil O-rings with the correct PAG oil (commonly PAG 46/ND-OIL8 as specified by Nissan/DENSO).
• Replace the receiver–drier whenever the system is opened to atmosphere.
• Vacuum for an adequate period to remove moisture, then leak-test and recharge by weight to the under-bonnet label spec.
• Verify steady vent temps and correct high/low-side pressures during the final check.

There’s no routine “maintenance” for a TXV beyond keeping the system leak-free and dry. If the system’s been contaminated (e.g., compressor failure or moisture ingress), the valve can gum up or clog with debris, so it’s smart to flush appropriate components, replace the drier, and renew the TXV during repairs. Given the labour to access the valve on an R50, many workshops recommend doing the drier at the same time to protect the fresh valve and compressor.

Technical sources referenced:

• Nissan Pathfinder 2000 (R50) Factory Service Manual, HA – Heating & Air Conditioning: system layout shows an expansion valve at the evaporator.
• Nissan Parts Catalogue (Expansion Valve/Group 92): lists the TXV for R50 Pathfinder model years around 2000.
• DENSO and Four Seasons A/C component catalogues: list a direct-fit thermal expansion valve for 1996–2004 Pathfinder.

Popular questions about the 2000 Nissan Pathfinder TX valve

Does a 2000 Nissan Pathfinder use a TX valve or an orifice tube?
It uses a TX valve. The R50 Pathfinder’s air-con is a TXV/receiver–drier style system rather than an orifice-tube/accumulator setup, as shown in the factory service manual and parts listings.

Where is the TX valve located on a 2000 Pathfinder?
It’s mounted at the evaporator inlet where the A/C lines meet the evaporator case at the firewall area. Access is typically from the passenger side and engine bay. The valve is a block-type unit retained with bolts and sealed by O-rings.

What are the signs the TX valve is failing on this model?
Tell-tales include inconsistent cabin temps, poor cooling at idle, frosting on the low-pressure line, compressor short cycling, and pressure readings that suggest a starved or flooded evaporator. After any TXV replacement, always vacuum, leak-test and recharge by weight.