Parts for your 1999 Nissan Navara-Tx valve

1999 Nissan Navara TX Valve — What It Does and How to Look After It

Based on the Nissan D22 Factory Service Manual (Heating & Air Conditioning, HA section) and common parts catalogues used in Australia and New Zealand for the D22 chassis, the 1999 Nissan Navara air-conditioning system is built around a thermostatic expansion valve (TX valve), not an orifice tube system. Those sources list the TX valve at the evaporator inlet, with a receiver–drier in the high side — a typical Japanese R134a setup of the era — making the TX valve absolutely relevant to this model.

The TX valve’s job is to meter refrigerant into the evaporator, reacting to evaporator outlet temperature and pressure so it keeps the evaporator just on the edge of icing for maximum cooling without freezing. On a 1999 Navara, when the TX valve is doing its thing, vent temps are steady, the compressor cycles sensibly, and fuel use stays reasonable on hot Kiwi and Aussie days.

There’s no real “service” item inside the valve itself, so it’s generally left alone until symptoms show up. Tell-tales of a crook TX valve include weak or fluctuating cooling at idle, frosty or sweating lines at the firewall, rapid compressor cycling, or scan-gauge/manifold readings that don’t stack up (very high high-side with a starved low-side, or vice versa). Because contamination can jam a TX valve, it’s smart to replace the receiver–drier and flush lines if the system’s been opened or a compressor has let go.

Replacement is a professional job, as venting refrigerant is illegal and dangerous. A licensed A/C tech will usually:

• Recover the R134a, then remove the glovebox/evaporator case to access the TX valve at the firewall.
• Replace the TX valve and all related O-rings, lightly oiling with the correct PAG oil specified by Nissan (commonly ND-8/PAG 46 — check the service data for the exact compressor on the vehicle).
• Fit a new receiver–drier any time the system is opened.
• Evacuate, leak-test (nitrogen/trace gas), then recharge by weight with R134a and the correct oil balance.

To keep the Navara’s TX valve happy long-term, ensure the condenser is clean and straight, the fan clutch/electric fans are doing their job, and the evaporator box drains freely. If cooling performance drops off, get pressures checked early — catching a sticky TX valve or moisture-laden drier before the compressor suffers will save a packet.

FAQs

Where is the TX valve on a 1999 Navara?
It’s mounted at the evaporator inlet, right at the firewall behind the glovebox. The high- and low-side pipes pass through the firewall to it. Access typically requires removing the glovebox and opening the evaporator case.

What symptoms point to a faulty TX valve on a D22?
Common signs are inconsistent cabin temps, frosting at the firewall fittings, a starved low side with sky‑high head pressure, noisy compressor cycling, or poor cooling at idle that improves on the open road. A manifold gauge set and temperature probe confirm the diagnosis.

Does this Navara use an orifice tube instead?
No — the 1999 D22 uses a TX valve with a receiver–drier. Orifice tube/accumulator systems were more common on some North American models, Nissan’s D22 in ANZ markets of this era is a TXV layout.