Parts for your 1998 Subaru Forester-Tx valve

1998 Subaru Forester TX-valve: fitment, purpose and servicing

For the 1998 Subaru Forester (SF series), a thermostatic expansion valve (TX-valve/TXV) is fitted to the factory R134a air‑conditioning system. This is confirmed by: Subaru Forester 1998 Service Manual — Heater & Air Conditioner section, which shows the evaporator and expansion valve assembly and outlines replacement, Subaru FAST genuine parts catalogue listing an “Expansion Valve” for MY98 Forester (commonly referenced as p/n 73520AC000), and DENSO A/C component catalogues that specify a block‑type TXV for Forester SF (1997–2002). These sources establish that an orifice‑tube setup is not used on this model.

What the TX‑valve does is simple but crucial: it meters liquid refrigerant into the evaporator, reacting to the temperature of the outlet pipe so the evaporator runs at the right superheat. That keeps cabin temps steady, protects the compressor from liquid slugging and helps prevent the evaporator from icing up. Because the valve responds to load (idling in traffic, climbing a hill, a frosty morning), it’s the brains of the Forester’s air‑con metering.

Owners typically don’t “service” the TX‑valve as a routine item, but it can wear, stick or become restricted by debris or moisture. Telltale signs include weak cooling at idle that improves with revs, vent temps that swing hot–cold, frost buildup at the valve or firewall, and odd gauge readings (very low low‑side or hunting pressures). If those symptoms show up, a proper diagnosis by a licensed air‑con technician is the go.

When replacement is needed, the right approach is: recover the refrigerant, access the evaporator/TXV behind the glove box area, replace the valve along with new O‑rings, and fit a new receiver‑drier any time the system is opened. Use the factory torque specs from the Subaru service manual, add the correct PAG oil type/quantity for any components changed, evacuate under vacuum, then recharge by weight to the specification on the under‑bonnet label. Pressure‑test with dry nitrogen before recharging to rule out leaks. If a cabin filter is fitted, renew it to keep airflow across the evaporator healthy.

A TX‑valve that’s doing its job makes the Forester feel cool quickly, stay comfortable on long drives, and keeps the compressor happy for the long haul. Cutting corners (reusing old O‑rings, skipping the drier, or charging “by feel”) usually leads to comebacks, so it’s worth doing once and doing right.

• Replace the TX‑valve if it’s leaking, blocked/contaminated, or confirmed faulty after pressure and temperature diagnostics.
• Always renew the receiver‑drier and applicable O‑rings, and recharge to the exact factory weight.
• Have a licensed technician handle refrigerant recovery and charging — it’s both law and best practice in AU/NZ.

Where is the TX‑valve on a 1998 Subaru Forester?
It sits at the evaporator inlet inside the HVAC case, typically behind the glove box. The refrigerant pipes pass through the firewall on the passenger side and bolt to the TX‑valve block mounted on the evaporator core.

Does a 1998 Forester use an orifice tube instead?
No. Technical references for the SF‑series 1998 Forester specify a thermostatic expansion valve with a receiver‑drier, not an orifice‑tube/accumulator setup. This is documented in the Subaru service manual’s HVAC section and the Subaru FAST parts listings for the model year.

What are the signs the TX‑valve needs replacement?
Common clues include poor cooling at idle, cycling or fluctuating vent temperatures, frosting near the valve or at the firewall, and abnormal gauge readings during diagnosis. After ruling out low charge, fan issues and a blocked condenser, a sticking or restricted TX‑valve is a prime suspect.