Parts for your 1993 Toyota Caldina-Tx valve

1993 Toyota Caldina TX valve: what it is, why it matters, and when to service it

Technical references confirm the 1993 Toyota Caldina uses a thermostatic expansion valve (TX valve). Toyota’s factory service manual for the ST19# Caldina platform lists a “Cooler Expansion Valve” in the air conditioning section, the Toyota Electronic Parts Catalogue names “VALVE, EXPANSION (FOR COOLER UNIT)” for the same chassis range, and DENSO’s A/C parts catalogue specifies a TX valve for Caldina models built in the early to mid‑1990s. So yes—this vehicle is TX‑valve equipped.

On a 1993 Caldina, the TX valve meters refrigerant into the evaporator based on temperature sensed at the outlet. By controlling superheat, it stops the evaporator from icing and prevents liquid refrigerant from reaching the compressor (no one wants a hydraulic lock). The result is steadier vent temps, better efficiency, and a compressor that lives a long, happy life.

When a TX valve starts playing up, owners may notice weak cooling at idle, vent temperatures that swing hot‑cold, frosting on the evaporator line, or pressure readings that are either too high or too low. Because the Caldina sits right in the R12/R134a changeover era, it’s important to confirm the refrigerant type on the under‑bonnet label—some cars remain on R12, many have been converted to R134a. Always match the correct PAG/mineral oil and O‑ring material for the gas in use.

Replacement and maintenance best practice on this model includes:

• Recovery and evacuation by a licensed A/C technician—venting refrigerant is illegal in AU/NZ.
• Replace the receiver‑drier whenever the system is opened, it protects the TX valve from moisture and debris.
• Use new, correct‑spec O‑rings lightly lubricated with the system oil, torque fittings to spec and avoid overtightening the valve body.
• Ensure the sensing bulb is clamped snugly to the evaporator outlet and insulated—poor bulb contact equals poor metering.
• Pressure‑test with nitrogen, deep vacuum to remove moisture, then recharge by weight to the factory spec for the refrigerant fitted.

While access is open, it’s a good time to check the evaporator core face for fluff and grime, and to clean out the HVAC drain. If a cabin filter is fitted (some markets weren’t), replace it to keep airflow up. Done right, the Caldina’s TX valve setup delivers crisp, consistent cooling even in a scorching Aussie or Kiwi summer.

Popular questions

Where is the TX valve on a 1993 Toyota Caldina?
It’s mounted at the evaporator inside the HVAC box, typically accessed by removing the glove box and related trims. The valve sits between the liquid line and the evaporator inlet, with its sensing bulb strapped to the evaporator outlet.

Should the receiver‑drier be replaced with the TX valve?
Yes. Any time the system is opened, the receiver‑drier should be renewed. It captures moisture and particulates that can quickly foul a fresh TX valve and damage the compressor.

How do I tell if the TX valve is the issue and not low refrigerant?
Low refrigerant usually shows as poor cooling all the time with low static pressure, while a sticking TX valve often causes cycling temps, frosting at the evaporator outlet, or abnormal high/low side pressures. Proper diagnosis with gauges and temperature measurements is the reliable way to call it.