Parts for your 2015 Holden Colorado-Tx valve

2015 Holden Colorado TX Valve — what it does and when to service it

Technical references confirm a TX valve is fitted to the 2015 Holden Colorado. The Holden RG Colorado Service Manual (HVAC section: A/C Refrigerant Expansion Valve Replacement) specifies a block‑type thermal expansion valve at the evaporator inlet, and the Holden/GM Electronic Parts Catalogue lists an Expansion Valve (TXV) for RG Colorado/Colorado 7 model years 2012–2016. DENSO HVAC technical literature and GM Service Information describe this TXV’s job: meter R134a into the evaporator to match heat load and maintain the right superheat.

On the Colorado, the TX valve sits at the firewall where the A/C pipes enter the cabin. It meters refrigerant based on evaporator outlet temperature/pressure, keeping the evaporator cold without icing. That means steadier vent temps, better performance at idle, and less compressor cycling compared with fixed orifice systems.

There’s no scheduled replacement for a healthy TXV, but a crook one can cause weak cooling, temperature “hunting”, iced lines, or odd pressure readings. Common triggers for replacement are contamination after a compressor failure, moisture ingress, or a stuck metering pin.

• Typical symptoms: warm air at idle then cold on the move, frosty or sweating pipes near the firewall, hiss that never settles, high low‑side pressure with low vent performance, or vacuum not holding during evacuation.
• Best practice when opening the system: replace the receiver–drier or desiccant bag (often integrated in the condenser on RG), renew all disturbed O‑rings, and use the specified PAG oil and R134a charge by weight as shown on the under‑bonnet label.

Replacement basics (workshop equipment required): recover the refrigerant, remove cowl/trim for access, disconnect the two lines at the valve, unbolt and swap the TXV, fit new lubricated O‑rings, torque to spec, pressure‑test with dry nitrogen, evacuate for 30–45 minutes, then recharge precisely by weight. Don’t flush through the TXV—remove it if flushing the evaporator. After charging, verify outlet temps, check for icing, and confirm stable high/low pressures. A clean cabin filter and good condenser airflow help the TXV do its job in Aussie and Kiwi summers.

Use OE or quality aftermarket valves that match the RG calibration. Over‑ or under‑charging the system will mask TXV control, so avoid “top‑ups” and always charge accurately.

Popular questions

Does a 2015 Holden Colorado actually have a TX valve?
Yes. Holden/GM service information and parts catalogues list a block‑type expansion (TX) valve for the RG Colorado, mounted at the evaporator inlet on the firewall.

Where is the TX valve on a 2015 Colorado?
Under the bonnet at the bulkhead/firewall where the A/C pipes enter the cabin. It’s a compact block clamped between the evaporator core fittings and the engine‑bay lines.

When should the TX valve be replaced?
There’s no time‑based interval. Replace it when there’s confirmed fault—poor cooling with correct charge, unstable vent temps, abnormal pressure readings, or contamination after compressor failure. When replacing, also renew the receiver–drier/desiccant and O‑rings, then evacuate and recharge by weight.