Parts for your 1991 Mitsubishi Pajero-Tx valve

1991 Mitsubishi Pajero TX-valve — what it does and how to look after it

Technical sources confirm the 1991 Mitsubishi Pajero uses a thermostatic expansion valve (TX-valve) in its factory air-conditioning system. The Mitsubishi Pajero Workshop Manual for the late-’80s to early-’90s models (Group 55 – Heater & Air Conditioner) shows a TX-valve bolted to the evaporator at the firewall. The Mitsubishi ASA/EPC parts catalogue for 1991 Pajero lists an “Expansion Valve” within the evaporator assembly. The Haynes Mitsubishi Pajero/Montero 1983–1997 manual also depicts a TXV-style, receiver–drier system for early-’90s models. This is the typical R12-era Japanese layout described in Sanden compressor service literature.

On a 1991 Pajero, the TX-valve meters refrigerant flow into the evaporator based on outlet temperature and pressure, keeping the evaporator just cold enough without freezing. That’s how it maintains steady cabin temps even when the rig is idling in traffic one minute and climbing a hill the next. It’s a precision bit of kit that works with the receiver–drier, evaporator, condenser and compressor to keep air-con performance smooth and efficient.

It’s not a routine “replace every X km” item, but it’s smart to inspect or replace the TX-valve whenever the system is opened, the compressor is replaced, or there are symptoms like inconsistent vent temps, icing on the evaporator case, a loud whoosh/hiss at the firewall, high low-side pressure, or very low suction with poor cooling. Contamination (desiccant dust, metal) can stick a TXV, so any time the system suffers a major failure, the valve deserves attention.

Replacement is straightforward in principle but best left to a licenced A/C technician. The system must be safely recovered, the glovebox and evaporator case accessed, and the valve unbolted from the evaporator tubes. Fresh O-rings (compatible with the refrigerant/oil in use) and correct torque are crucial. Always replace the receiver–drier when the system’s been open, flush if contamination is suspected, evacuate to deep vacuum, then recharge by weight. If the Pajero’s been converted from R12 to R134a, confirm the TX-valve is R134a-compatible and the correct oil (PAG or POE, depending on component mix) is used. Insulating the sensing bulb and routing it as per the manual helps avoid hunting and keeps superheat control tidy.

Legal bit: in Australia and New Zealand, refrigerant handling requires a licenced technician and compliant equipment. That protects the system, the environment and the owner’s wallet.

• Typical location: mounted on the evaporator at the firewall, accessed from the passenger side behind the glovebox.
• Good practice: replace receiver–drier, renew O-rings, check for contamination, and verify charge by weight after any TXV work.

Popular questions about 1991 Mitsubishi Pajero TX-valve

Where is the TX-valve on a 1991 Pajero?
It’s fixed to the evaporator block at the firewall side of the HVAC case, typically accessed from inside the cabin behind the glovebox. Lines pass through the firewall to the engine bay. Removing the glovebox and some HVAC trim gives access to the valve and sensing bulb.

Does a 1991 Pajero use a TX-valve or an orifice tube?
It uses a TX-valve with a receiver–drier, not an orifice tube/accumulator setup. This is documented in Mitsubishi’s workshop manual and parts catalogue for the 1991 model year and is typical of period Mitsubishi A/C system design.

When should the TX-valve be replaced?
Replace it if there are clear symptoms of metering faults, during a major A/C overhaul, after compressor failure, or any time the system is opened and contamination is suspected. Pair the job with a new receiver–drier, fresh O-rings, proper evacuation and a weighed recharge.