Parts for your 2007 Mazda Premacy-Tx valve

2007 Mazda Premacy TX valve: what it does, where it sits, and how to look after it

Based on technical references, the 2007 Mazda Premacy (CR chassis, also known as Mazda5 in some markets) is fitted with a thermal expansion valve (TX valve). The Mazda workshop manual for the CR-series HVAC system details removal and installation of the TX valve at the evaporator, Mazda’s electronic parts catalogue lists an A/C expansion valve for Premacy CR models, and DENSO component catalogues show a matched expansion valve for the same vehicle family. So yes—this model absolutely uses a TX valve.

The TX valve’s job is to meter liquid R‑134a into the evaporator, matching flow to heat load while maintaining correct superheat. That precise control keeps vent temps cold without freezing the core, stabilises pressures, and helps the compressor live a long, easy life. On the Premacy, the valve is a block-type unit mounted at the evaporator connections on the firewall, working with the condenser’s built‑in desiccant to keep the air‑con crisp even on scorcher days.

There’s no routine “service interval” for the TX valve itself, but it should be inspected whenever the A/C system is opened. If performance is poor or pressures are erratic, a new valve is sensible insurance. Replacement is straightforward for a trained tech: recover the refrigerant, access the valve at the firewall, replace the valve and O‑rings, then evacuate and recharge to the specification on the under‑bonnet label. Best practice is to renew the receiver/drier or desiccant bag in the condenser whenever the circuit has been open, fit new green HNBR O‑rings, and add the correct type and amount of PAG oil as specified by Mazda. A proper vacuum hold test and precise R‑134a charge make or break the result—guessing the charge will give so‑so cooling and can mask a TX valve issue.

• Common signs the TX valve needs attention:
  • Warm air at idle, then sudden bursts of cold
  • Frosting on one evaporator line or the valve body
  • Hunting or whooshing noises from the dash area
  • High side pressure too low or low side pulled down abnormally on gauges
  • Metallic debris in the old valve (points to a bigger system clean-out)

Look after the basics—clean condenser fins, a fresh cabin filter, and correct refrigerant charge—and the Premacy’s TX valve will keep doing its quiet, clever metering in the background.

Popular questions about the 2007 Mazda Premacy TX valve

Where is the TX valve located on a 2007 Premacy?
It’s mounted at the evaporator connections on the firewall, where the two A/C pipes pass through. On most vehicles it’s accessed from the engine bay, removing the wiper cowl can make room for tools. The evaporator itself lives inside the HVAC case behind the dash, but the valve can usually be changed without pulling the dashboard.

Should the TX valve be replaced during every A/C repair?
Not automatically. If the system’s been open for a while, there’s contamination, or pressures/vent temps point to a metering fault, replacement is wise. Any time a compressor fails or metal is found, the TX valve should be renewed as part of a full clean‑out with desiccant replacement and a precise recharge.

What refrigerant and oil should be used after TX valve replacement?
The 2007 Premacy uses R‑134a. Charge to the exact mass on the under‑bonnet label. Use the Mazda‑specified PAG oil type and quantity for the CR chassis, only add the amount appropriate for the components replaced, and always perform a deep vacuum and leak check before recharging.