Parts for your 2004 Toyota Caldina-Tx valve

2004 Toyota Caldina TX‑Valve: What it does and how to look after it

Based on Toyota’s Electronic Parts Catalogue for the T240-series Caldina (ZZT241, AZT241/246, ST246) and the Toyota air conditioning repair manual sections for this platform, the 2004 Toyota Caldina uses a thermal expansion valve (TX‑valve) at the evaporator inlet. DENSO service documentation for Toyota R134a systems of this era also specifies a thermostatic expansion valve rather than an orifice tube, confirming the TX‑valve is the factory metering device on these models.

The TX‑valve is the brains of the Caldina’s A/C cooling circuit. It meters liquid R134a into the evaporator based on temperature sensed by its bulb and line pressure, keeping superheat in the sweet spot so the cabin gets strong, consistent cool without icing the core. When it’s healthy, you get quick pull‑down on hot days, stable vent temps, and happy highway and city performance.

It’s not a routine replacement item, but it does deserve attention during A/C servicing. A sticky or blocked TX‑valve can mimic low‑gas symptoms or cause frost on the suction line. Typical signs include:

• Weak or wandering cabin temps, especially after a hot soak
• Frosting at the evaporator outlet or hissing that comes and goes
• High high‑side and low low‑side pressures on the gauges, or the reverse if stuck open
• Short‑cycling of the compressor

On the 2004 Caldina, the TX‑valve is mounted at the evaporator within the HVAC case behind the glovebox area. Replacing it is a pro job because refrigerant must be recovered and the cooler unit opened. A good workshop approach is:

1. Recover refrigerant, disconnect battery, remove glovebox/trim to access the HVAC case
2. Undo A/C lines at the firewall and split the case to reach the evaporator and TX‑valve
3. Replace the valve and all O‑rings, lightly oiling new seals with the specified PAG oil
4. Reassemble, evacuate for at least 30 minutes, leak‑test, then charge R134a by weight to the spec on the bonnet decal

Because incorrect torque or contamination can cause leaks or erratic operation, stick to factory procedures and torque values from the Toyota repair manual. As part of regular servicing, keep the cabin filter clean for good airflow, wash the condenser fins, run the A/C weekly year‑round, and check for oily residue at hose joints. If the system shows the symptoms above, a licensed A/C tech should confirm with pressure diagnostics before calling the TX‑valve.

FAQs

Does the 2004 Caldina run a TX‑valve or an orifice tube?
It runs a TX‑valve across the 2004 range (ZZT241, AZT241/246, ST246). Toyota’s EPC lists the expansion valve as part of the cooler unit, and workshop procedures cover TX‑valve removal/installation at the evaporator.

Where is the TX‑valve located and how hard is it to change?
It’s fitted on the evaporator inside the HVAC case behind the glovebox area. The dash doesn’t usually need full removal, but interior trim and the cooler case must be opened. Expect a few hours’ labour plus an evac/recharge.

What refrigerant and oil should be used?
The 2004 Caldina uses R134a. Charge by weight to the figure on the under‑bonnet label and use the Toyota‑specified PAG oil type and quantity noted in the factory manual. Don’t mix refrigerants.