Parts for your 1990 Mitsubishi Pajero-Tx valve

1990 Mitsubishi Pajero TX Valve — What it does and how to look after it

Yes, the 1990 Mitsubishi Pajero is fitted with a TX (thermostatic expansion) valve. This isn’t guesswork: the Mitsubishi Pajero Factory Service Manual (Group 55 – Heater, Air Conditioner and Ventilation, late-1980s to early-1990s editions) describes a thermostatic expansion valve at the evaporator inlet, and DENSO’s application catalogues for the L040/L044 Pajero list an expansion valve for this model. Gregory’s Service and Repair Manual covering Pajero 1983–1996 also outlines valve removal behind the glovebox. On right‑hand‑drive Australia/NZ vehicles, the TX valve sits at the evaporator entry, typically accessed by removing the glovebox, the hard lines pass through the firewall on the passenger side under the bonnet.

The TX valve meters refrigerant flow into the evaporator based on outlet tube temperature and pressure, keeping evaporator superheat in the sweet spot. Get it right and the cabin cools quickly without freezing the core, efficiency is up, and compressor load stays sensible. When the valve sticks, clogs, or mis-meters, you’ll see tell‑tales like weak or wildly fluctuating cooling, evaporator icing, hissing, or a compressor short‑cycling its head off.

As part of routine air‑con servicing on a 1990 Pajero, the TX valve deserves a check whenever the system is opened, performance drops, or metal/debris is found. If replacing it, match the valve calibration to the refrigerant in the vehicle (many 1990s Pajeros were R12 new, plenty have been retrofitted to R134a). Always renew the receiver‑drier and O‑rings, and use the correct oil: mineral for R12, PAG for R134a, or ester oil for many retrofits. A proper vacuum, leak test, and weight‑specific recharge are non‑negotiable.

• Recover the refrigerant with licensed equipment (it’s the law in AU/NZ).
• Remove the glovebox/trim to expose the evaporator and TX valve.
• Crack the line fittings, cap them, and lift out the old valve and bulb.
• Fit the new valve, new O‑rings (lightly oiled), and correctly position the sensing bulb.
• Replace the receiver‑drier, flush lines and condenser if contamination is suspected.
• Evacuate, leak‑test, add the right oil charge, then recharge by weight.

If the system’s been contaminated or the compressor has failed, go the extra mile: flush, fit a drier, sometimes a condenser, and the TX valve. That’s the difference between a quick fix and an air‑con that stays cold for years.

Popular questions about 1990 Mitsubishi Pajero TX valves

Where is the TX valve on a 1990 Pajero?
It’s mounted at the evaporator inlet behind the glovebox on RHD models in Australia and New Zealand. You’ll see the two A/C lines heading through the passenger‑side firewall, trace them back to the compact alloy valve on the evaporator.

What are the symptoms of a failing TX valve?
Common signs include poor or inconsistent cooling, frost or ice on the evaporator or suction line, hissing at the valve, and rapid compressor cycling. After a compressor failure, debris can lodge in the valve and starve the evaporator.

Do TX valves need regular replacement?
They aren’t a scheduled replacement item, but any time the system is opened, contaminated, or retrofitted to a different refrigerant, assessing or replacing the TX valve (and always the receiver‑drier) is smart practice.