Parts for your 2015 Toyota Bb-Tx valve

2015 Toyota bB TX-valve: what it does, when to replace it, and how to look after it

Technical sources confirm the 2015 Toyota bB (QNC2# series) uses a thermal expansion valve (TX‑valve) in its air‑conditioning system. Toyota’s Electronic Parts Catalog for the bB lists a “Valve, Expansion (for Cooler)” for 2015 models (e.g., 88515‑52XXX, part number varies by spec). The Toyota Repair Manual A/C section for QNC2# includes procedures titled “Cooler Expansion Valve – Removal/Installation/Inspection,” and Denso HVAC training materials describe Toyota’s use of block‑type TX‑valves at the evaporator on vehicles of this era. So yes—this model is TX‑valve equipped.

On the 2015 bB, the TX‑valve meters liquid R‑134a into the evaporator based on evaporator outlet temperature and pressure, keeping cabin temps steady without freezing the core. It’s a small, block‑style valve mounted at the evaporator case, and when it’s doing its job, you get quick pull‑down on a hot day, stable vent temps, and a compressor that isn’t working harder than it should.

TX‑valves aren’t a routine service item, but they do wear or stick when contaminants or moisture get into the system. Common clues include weak cooling at idle but better at speed, frosting at the valve or evaporator, a compressor short‑cycling, or pressure readings that are abnormally high or low for the ambient conditions. Before blaming the valve, a good tech will check the cabin filter, condenser airflow, fan operation and charge level.

• Replacement basics: Because the A/C circuit must be opened, the job should be handled by an ARCtick‑licensed A/C tech in Australia or a suitably certified refrigeration technician in New Zealand.
• Best practice: Recover the refrigerant, replace the TX‑valve and all disturbed O‑rings, and fit a new receiver/drier or desiccant bag whenever the system has been opened.
• Reassembly: Lubricate new O‑rings with the correct PAG oil, evacuate (deep vacuum) to remove moisture, pressure‑test for leaks, then recharge with R‑134a to the exact amount on the under‑bonnet label.

Looking after it is straightforward: run the A/C for 10–15 minutes every few weeks to circulate oil through the TX‑valve, keep the condenser clean of bugs and debris, and change the cabin filter on schedule so the evaporator doesn’t ice up. If the system’s been open to air, don’t delay repairs—moisture is the TX‑valve’s enemy. With the right servicing steps, the bB’s TX‑valve will keep the cabin cool and the compressor happy for years.

• Does the 2015 Toyota bB use a TX‑valve or an orifice tube?
  It uses a TX‑valve. Toyota’s EPC for the QNC2# bB lists a “Valve, Expansion (for Cooler),” and the factory repair manual includes TX‑valve service procedures.
• When should the TX‑valve be replaced on a 2015 bB?
  It’s not a scheduled item. Replace it if it’s sticking or metering poorly (symptoms like frosting, erratic pressures, weak cooling), or whenever the system has been contaminated or left open—ideally alongside a new receiver/drier.
• What refrigerant and charge does the bB A/C take?
  R‑134a. Charge to the exact mass shown on the vehicle’s under‑bonnet label. If that label is missing, a licensed A/C technician can access the correct spec via the Toyota service information.