Parts for your 1988 Mitsubishi Pajero-Tx valve

1988 Mitsubishi Pajero TX‑Valve: What it is, where it lives, and how to look after it

Yes, the 1988 Mitsubishi Pajero runs a thermal expansion valve (TX‑valve) in its air‑conditioning system. This is shown in the Mitsubishi Factory Service Manual (Group 55: Heater, Ventilation & Air Conditioning), the Mitsubishi ASA electronic parts catalogue for late‑1980s Pajero/Montero models, and DENSO’s aftermarket listings for L040‑series Pajero, all of which depict an expansion valve mounted at the evaporator inlet.

The TX‑valve’s job is to meter refrigerant into the evaporator based on temperature and pressure at the outlet, keeping superheat in the sweet spot so the core doesn’t ice up and the compressor isn’t slugged with liquid. On a 1988 Pajero (originally R12), the valve sits on the evaporator under the passenger side of the dash, with a sensing bulb strapped to the evaporator outlet. When it’s behaving, you get steady vent temps and decent cooling around town and on the open road.

Thinking about servicing or replacement? It’s a good idea when the system’s open for other work, or if you’re retrofitting to R134a. Many owners replace the TX‑valve with an R134a‑compatible unit, fit new HNBR (green) O‑rings, and install a fresh receiver‑drier. Always have a licensed air‑con tech recover any remaining gas, then vacuum the system before charging to the correct weight for your refrigerant. If converting from R12, use the valve, oil and charge guidelines specified for R134a, the charge is typically lower by roughly 10–15%, but follow the service data for your exact setup.

• Common symptoms of a tired TX‑valve: weak cooling at idle, frosty or sweating lines near the firewall, rapid cycling, uneven vent temps, or odd high/low pressure readings.
• Best practices: replace the receiver‑drier whenever the system is opened, insulate and secure the sensing bulb correctly, use the specified torque on flare/nut fittings, and check for leaks with dye or nitrogen/soap before re‑gassing.

While the Pajero doesn’t have a factory pollen filter, keeping the evaporator case clean and drains clear helps airflow and reduces icing complaints that can be mistaken for TX‑valve issues. If the system’s otherwise healthy and pressures look normal, a judicious clean and leak check can save chasing ghosts under the dash.

Popular questions

Where is the TX‑valve on a 1988 Pajero?
It’s mounted on the evaporator inside the HVAC case behind the glovebox on the passenger side. Access usually involves glovebox and trim removal, then carefully loosening the refrigerant line fittings and opening the evaporator case.

What are the signs my TX‑valve is failing?
Expect weak or intermittent cooling, frosting at the evaporator inlet/outlet, rapid compressor cycling, or vent temps that swing hot–cold. A proper gauge set reading will often show abnormal pressure differential or unstable low‑side pressure.

Can I keep the original TX‑valve when converting to R134a?
You can, but it’s smarter to fit an R134a‑calibrated valve, renew all O‑rings, flush if needed, replace the receiver‑drier, and recharge to the specified R134a mass. This improves reliability and cooling performance in Aussie and Kiwi summers.