Parts for your 2010 Subaru Impreza-Tx valve

2010 Subaru Impreza TX valve — what it does, where it lives, and when to replace it

Technical sources confirm the 2010 Subaru Impreza uses a thermal expansion valve (TX valve) in its factory air-conditioning system, so it’s absolutely relevant to this model. References include: Subaru Workshop/Service Manual for 2010MY Impreza (HVAC – Air Conditioner System, “Expansion Valve”), Subaru Genuine Parts Catalogue listing an A/C expansion valve for 2010 Impreza models (e.g., P/N 73521FG000 and supersessions), and DENSO HVAC application data for GE/GH Impreza indicating a TXV-based system. That means no orifice tube/accumulator setup here — it’s a TXV with a receiver-drier.

The TX valve meters the exact amount of refrigerant into the evaporator based on temperature and pressure, keeping superheat in the sweet spot. In plain speak, it helps the air-con blow nice and cold without icing the core or drowning the compressor. On the 2010 Impreza, it’s a block-style valve mounted at the evaporator inlet (under the dash at the firewall side), sealed with O-rings. When it’s healthy, you get steady vent temps, solid pull-down on hot days, and happy highway and city cooling alike.

There’s no routine “maintenance” on a TX valve, but it becomes a must-check item any time the A/C performance goes off. If the system’s been opened (say, due to a leak repair), best practice is to replace the receiver-drier, renew all disturbed O-rings with HNBR types, add the correct PAG oil amount, evacuate properly, and recharge to the exact R‑134a mass shown on the under‑bonnet decal. A sticky or clogged TXV can cause frost at the valve, vent temps that swing hot–cold, a starved evaporator, or odd gauge readings.

• Common hints the TX valve’s unhappy:
  • Poor cooling at idle but better on the move, or vice versa
  • Frost or sweating on the evaporator pipes near the firewall
  • Low-side pressure abnormally low or hunting, high-side too high
  • Vent temps fluctuating or slow cabin cool-down
• Service tips for the Impreza:
  • Access is under the dash at the evaporator, follow the Subaru torque specs
  • Always use new green HNBR O-rings with a smear of the correct PAG oil
  • Replace the receiver-drier whenever the circuit’s opened
  • Charge by weight, not “by feel” — use the bonnet decal spec

Because handling refrigerant is regulated in Australia and New Zealand, it’s wise to leave TX valve diagnosis and replacement to a licensed air‑con technician. They’ll pressure-test with nitrogen, vacuum the system, and verify superheat/subcool targets so the Impreza’s air-con stays crisp all summer.

Where is the TX valve on a 2010 Subaru Impreza?

It’s a block-style valve at the evaporator inlet, inside the cabin on the firewall side of the HVAC case. From the engine bay you’ll see the two A/C pipes entering the bulkhead, the valve sits just inside, secured to the evaporator core. Access generally requires working under the dash and carefully separating the pipe joints to the valve.

What symptoms point to a failing TX valve versus low refrigerant?

Both can cause weak cooling, but a bad TXV often gives fluctuating vent temps, frost on the evaporator inlet, and “hunting” low-side pressure. Low refrigerant usually shows consistently low low‑side pressure, warm air at idle and cruise, and oil dye/leak evidence. A proper gauge set and temperature checks help tell them apart.

Should the receiver‑drier be replaced when changing the TX valve?

Yes. Any time the system is opened, replace the receiver-drier to protect the new valve and compressor from moisture and debris. Renew O-rings, add the correct PAG oil amount for components replaced, evacuate thoroughly, and recharge to the exact R‑134a mass on the vehicle label.