Parts for your 2008 Subaru Impreza-Tx valve

2008 Subaru Impreza TX Valve: What It Does and When to Replace It

Based on technical sources, a thermal expansion valve (TX valve) is definitely fitted to the 2008 Subaru Impreza (GE/GH). The Subaru Impreza 2008 Service Manual (HVAC section) specifies an expansion valve at the evaporator inlet, and Subaru’s genuine parts catalogue lists an A/C Expansion Valve for this model range (commonly referenced under part numbers in the 73520FG000 family). This is a TXV-style R134a system with a receiver-drier, not an orifice-tube/accumulator setup.

The TX valve meters refrigerant into the evaporator to keep superheat in the sweet spot. That keeps vent temps nice and cold without letting the core ice up or the compressor cop a hiding. On the 2008 Impreza it works alongside the receiver-drier and condenser to deliver steady cooling across Aussie and Kiwi summers, even when the weather flips from cool mornings to hot arvos.

Typical symptoms of a crook TX valve include weak or on–off cooling, frosty or sweating pipes near the firewall, constant hissing, or pressure readings that don’t stack up (high high-side with a starving low-side). Because it’s mounted at the evaporator block behind the glovebox, access is inside the cabin where the refrigerant lines pass through the firewall.

There’s no routine “maintenance” for a TX valve, but good practice during A/C servicing helps it last:

• Always replace O-rings and lightly lubricate with the correct PAG oil when lines are opened.
• Evacuate, leak-test, and recharge to the label spec after any A/C work.
• Fit a new receiver-drier if the system’s been open or after a compressor failure, and flush lines as required.

Replacement pointers for the 2008 Impreza’s TX valve:

1. Recover the refrigerant legally (ARCtick in AU, approved handlers in NZ).
2. Remove the glovebox to access the HVAC case and valve connections.
3. Crack the line fittings, catch the old O-rings, and swap in the new valve.
4. Use new O-rings, torque fasteners to the service manual spec, then vacuum and recharge.

Handy tip: If vent temps wander or the system cools fine on the move but not at idle, the TX valve and condenser airflow are high on the list to check. A licensed tech can confirm with manifold gauges and a superheat check at the evaporator outlet.

Popular questions about the 2008 Subaru Impreza TX valve

Where is the TX valve on a 2008 Subaru Impreza?
It’s mounted at the evaporator block inside the cabin, typically behind the glovebox where the A/C lines come through the firewall. Access is from the passenger side, which makes interior trim removal part of the job.

How often should the TX valve be replaced?
There’s no set interval. It’s replaced when faulty—stuck, restricted, or leaking—or any time the system has suffered contamination (like a compressor failure). If the system’s been open to air, the receiver-drier should be renewed and the valve assessed.

Can you drive with a failing TX valve?
Usually, yes—but cooling performance will be poor and the compressor may be stressed if the valve is badly restricted. It’s best to get it diagnosed promptly and serviced by a licensed A/C technician.