Parts for your 2007 Toyota Bb-Tx valve

2007 Toyota bB TX Valve – Fitment, Purpose and Service Advice

Based on technical sources, the 2007 Toyota bB (QNC20/QNC21 series) is fitted with a thermal expansion valve (TX valve). Toyota’s Electronic Parts Catalogue lists a “cooler expansion valve” in the Heating & Air Conditioning section for these models, and the Toyota Repair Manual includes a specific remove/replace procedure for the expansion valve at the evaporator unit. DENSO service literature notes Toyota passenger vehicles of this era typically use a block‑type externally equalised TXV mounted at the evaporator inlet, which aligns with the bB’s HVAC layout. Reputable aftermarket catalogues likewise list a direct‑fit expansion valve for 2007 bB applications, further confirming fitment.

The 2007 Toyota bB’s TX valve meters refrigerant into the evaporator so the cabin cools efficiently without freezing the core. It responds to evaporator outlet temperature and pressure, trimming flow so the evaporator runs at the sweet spot. That’s why a healthy valve gives stable vent temps, decent cooling at idle, and no frost-up on the pipes.

While the TX valve isn’t a “wear item”, the bB benefits from a check during any A/C service. If the cabin air is only cool while driving, there’s random surging from cold to lukewarm, or there’s ice on the suction line, the valve may be sticking or starved. A proper diagnosis uses manifold gauges (or a scan tool on systems with pressure sensors) to confirm low-side/ high-side behaviour before parts are swapped.

On the bB, the TX valve sits at the evaporator in the HVAC case, accessible from the passenger side after removing trim/glovebox and disconnecting the two A/C pipes at the firewall. Replacement is straightforward for a trained tech, but it’s critical to keep things surgically clean. Best practice includes:

• Recover the refrigerant with certified equipment, then cap open lines immediately.
• Replace all disturbed O‑rings and lightly oil them with the correct PAG oil spec for this model.
• Renew the receiver/drier (or desiccant bag) whenever the system is opened, especially if the valve is being replaced.
• Evacuate to deep vacuum and recharge with the factory‑specified R‑134a mass, don’t guess by pressure.

If the system suffered a compressor failure, have the lines and condenser (if serviceable) cleaned appropriately, don’t flush the TX valve or compressor. A fresh cabin filter helps overall airflow, and periodic leak checks with UV dye or an electronic detector will keep the bB’s air‑con crisp for Aussie and Kiwi summers.

Popular questions

Does the 2007 Toyota bB use a TX valve or an orifice tube?
It uses a TX valve. Toyota’s parts and service information for the QNC20/QNC21 confirms a block‑type expansion valve at the evaporator inlet, not an orifice tube.

Where is the TX valve on a 2007 bB?
It’s mounted on the evaporator inside the HVAC case behind the dash, with the liquid and suction pipes joining through the firewall on the passenger side. Access is typically via the glovebox area.

Should the receiver/drier be replaced when changing the TX valve?
Yes. Any time the system is opened, renewing the receiver/drier (or desiccant bag) is recommended to control moisture and protect the new valve and compressor.