Parts for your 2020 Mazda 3-Tx valve

2020 Mazda 3 TX Valve: What it does and how to look after it

Referencing technical sources, the 2020 Mazda 3 (BP) does use a thermal expansion valve (TX valve). Mazda’s Workshop/Service Manual for the BP-series Mazda 3 (HVAC section: Air Conditioner System – Expansion Valve Removal/Installation) specifies a block-type expansion valve at the evaporator. The Mazda Electronic Parts Catalogue (EPC) for BP-series vehicles also lists an “Expansion Valve” within the A/C section. That means the TX valve is absolutely relevant to the 2020 Mazda 3’s air-con system.

On this model, the TX valve meters the exact amount of refrigerant entering the evaporator, keeping the evaporator just cold enough to absorb heat without freezing. It helps the Mazda 3’s climate control stay steady in Aussie and Kiwi conditions, working with the variable displacement compressor to deliver quick cool-downs, stable cabin temps, and decent fuel efficiency. When the TX valve is healthy, it maintains proper superheat and keeps the system pressure balance where it should be.

The valve is mounted at the evaporator, near the firewall, and relies on clean, dry refrigerant. It’s not a routine “service item”, but it’s critical. If the system’s been contaminated (for example, after a compressor failure) or moisture has got in, the TX valve can stick or clog. Replacing it is a professional job: recover the refrigerant, disconnect the lines at the bulkhead, swap the valve and O-rings, evacuate, leak-test, and recharge by weight to the label under the bonnet. On these cars, it’s good practice to renew the receiver/drier (often integrated with the condenser) when the circuit is opened, and to add the correct amount of PAG oil for any parts replaced.

• Common signs of a crook TX valve: weak cooling at idle or cruise, cabin temperature swings, frosting at the firewall fittings or lines, rapid compressor cycling, and odd high/low gauge readings.
• Helpful preventative steps: keep the cabin filter and condenser clean, fix any leaks promptly, and only charge with the correct gas and oil as per the under-bonnet sticker.

If the compressor has let go (metal in the lines), plan on a TX valve, condenser/drier, thorough flushing (where applicable), and meticulous re-assembly. In Australia and New Zealand, refrigerant handling must be done by a licensed air-con technician, so it’s best left to the pros to protect both the system and your warranty.

• Does the 2020 Mazda 3 use a TX valve or an orifice tube?
  The 2020 Mazda 3 uses a thermal expansion valve (TXV), not an orifice tube. This is documented in Mazda’s BP-series service information under HVAC procedures covering expansion valve removal and installation, and it appears in the Mazda EPC as an “Expansion Valve” in the A/C parts listing.
• When should the TX valve be replaced on a 2020 Mazda 3?
  There’s no fixed replacement interval. Replace it if there are symptoms of metering faults (poor cooling, frosting, pressure irregularities), confirmed blockage, leaks, or after a compressor failure/contamination event. Any time the system is opened, use new O-rings, evacuate thoroughly, and recharge to spec.
• Is TX valve replacement a DIY job?
  Not really. The job involves refrigerant recovery, cleanliness standards, and correct recharging by weight. In Australia and New Zealand, only licensed technicians can legally handle refrigerant. Professional equipment and know‑how help avoid repeat failures and keep the air-con performing as it should.