Parts for your 1999 Toyota Altezza-Tx valve

1999 Toyota Altezza TX Valve — What It Does and How To Look After It

Based on technical documentation — including the Toyota Electronic Parts Catalogue (XE10 platform), the Lexus IS200/Altezza workshop manual (Air Conditioning section), and Denso A/C service literature — the 1999 Toyota Altezza runs a thermostatic expansion valve (TX valve) in its R134a climate control system, rather than an orifice tube. It’s mounted at the evaporator assembly and meters refrigerant into the core.

The TX valve is the little brain of the Altezza’s A/C. It regulates how much liquid refrigerant enters the evaporator, using a sensing bulb to track outlet superheat. When it’s doing its thing, the cabin gets cold quickly, the evaporator doesn’t ice up, and the compressor isn’t overworked. If the valve sticks or clogs, they’ll often notice inconsistent vent temps, weak cooling at idle, or frost forming on the suction line near the firewall. Technicians also see tell-tale pressure readings (very low suction or erratic swing) during gauge testing.

Servicing-wise, the TX valve is a sealed-system component, so it’s not a DIY “top-up and go.” Any work that opens the A/C loop needs refrigerant recovery, vacuum, and recharge by an ARCtick-licensed tech in Australia or the appropriate certified handler in New Zealand. On the Altezza, the valve sits at the evaporator block behind the glovebox, where the two A/C lines pass through the firewall. Access typically involves glovebox and trim removal, line disconnection, and careful extraction of the valve from the evaporator block.

• Always replace the O-rings and lightly oil them with the specified A/C oil before refitting.
• If the system’s been open or the TX valve has failed with debris, replace the receiver/drier and consider a system flush to protect the compressor.
• Torque the fittings to the factory spec in the service manual and support the lines to avoid bending or stressing them.

Good maintenance goes beyond the valve itself. A clogged cabin filter or poor condenser airflow under the bonnet can mimic a lazy TX valve by driving pressures out of whack, so it pays to keep those basics tidy. After reassembly, a proper deep vacuum and a precise R134a charge to the placard spec are essential for sharp, quiet cooling. Use the manufacturer-specified A/C oil type and quantity (Toyota/Denso ND-OIL equivalent), then leak-test and run the system to verify stable vent temps and steady pressures. Looked after properly, the Altezza’s TX valve will deliver crisp, reliable chill on the hottest Aussie or Kiwi afternoons.

Popular questions about the 1999 Toyota Altezza TX valve

Where is the TX valve located on a 1999 Toyota Altezza?
The TX valve is mounted at the evaporator block behind the glovebox area. The A/C pipes pass through the firewall into the HVAC case, where the valve bolts to the evaporator core. Access is from inside the cabin after removing the glovebox and surrounding trim.

What are common signs the TX valve needs replacing?
Expect weak or fluctuating cooling, frosty suction lines near the firewall, hissing that comes and goes, and pressure readings showing very low or erratic suction. A pro will confirm with gauges and temperature measurements before calling it.

Do I have to replace the receiver/drier when changing the TX valve?
It’s strongly recommended. Any time the system’s opened, the drier can saturate with moisture. Replacing it helps protect the compressor and ensures the new TX valve isn’t fighting contamination.