Parts for your 1999 Daihatsu Gran move-Tx valve

1999 Daihatsu Gran Move TX Valve: What It Does, Where It Lives, and When To Sort It

Based on factory-style documentation for the Daihatsu Gran Move/Pyzar G3-series air-conditioning system and common DENSO HVAC architecture of the era, the 1999 Gran Move uses a thermostatic expansion valve (often called a TX valve or TXV) at the evaporator inlet. Technical parts catalogues from major A/C suppliers also list an “expansion valve” specifically for this model, confirming it’s a TXV-type system with a receiver–drier rather than an orifice-tube setup.

The TX valve’s job is to meter R134a into the evaporator and keep the outlet superheat in the sweet spot. That means it matches refrigerant flow to load, stops the evaporator from icing up, and helps the cabin cool quickly without wasting energy. Because it constantly balances pressure and temperature, a healthy TXV is a big deal for stable vent temps on scorching Aussie and Kiwi summer days.

While a TX valve isn’t a routine service item, it can wear or get contaminated. Common clues it’s on the fritz include slow or uneven cooling, frosty lines at the firewall, vent temps that swing hot–cold, or weird gauge readings (low low-side/high high-side, or vice versa). Gummed-up desiccant, moisture, or debris can make the pintle stick. If the system’s been open to air or has a history of compressor issues, the TXV is a suspect.

On the Gran Move, the TX valve is mounted at the evaporator (inside the HVAC case, typically accessed from the passenger side area). Replacing it properly means recovering the refrigerant, removing the lines at the firewall, and splitting the case or service cover to reach the valve. In Australia and New Zealand, refrigerant handling must be done by a licensed technician (ARCtick in AU, approved refrigerant handlers in NZ).

• Always replace O-rings and lightly oil them with the correct PAG oil grade specified for the Gran Move.
• It’s best practice to fit a new receiver–drier whenever the system is opened or the TXV is replaced.
• Pull a deep vacuum (at least 30 minutes), verify it holds, then recharge to the stated R134a mass.
• If the old TXV had debris, inspect/flush lines and the condenser, don’t send junk into a fresh compressor.

A tidy TX valve keeps the Gran Move’s A/C consistent, efficient, and ready for a long summer haul. If in doubt, get a licensed A/C specialist to test superheat, pressures, and the sensor bulb seating on the valve before calling it.

Popular questions

Where is the TX valve on a 1999 Daihatsu Gran Move?
It’s fitted at the evaporator inlet inside the HVAC box, typically accessed from the passenger side area near the firewall. The refrigerant lines pass through the firewall to the valve. Access often requires partial dash or HVAC case disassembly, so allow time.

What are the symptoms of a failing TX valve on a Gran Move?
Expect weak or intermittent cooling, vent temps that surge, frost or sweating on the low-side line, and pressure readings that don’t make sense. After a compressor failure or contamination event, a sticking TXV is common until the system’s cleaned and the drier replaced.

Do I need to replace the receiver–drier when changing the TX valve?
Yes, best practice is to replace the drier any time the system is opened. It captures moisture and debris that can jam the new TXV and shorten compressor life. It’s an inexpensive bit that protects the whole setup.