Expansion Valves
Thermostatic expansion valves (TXV) and orifice tubes regulate refrigerant flow through the A/C evaporator. Critical for proper A/C performance.
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Thermostatic expansion valves (TXV) and orifice tubes regulate refrigerant flow through the A/C evaporator. Critical for proper A/C performance.
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The thermal expansion valve (TXV) controls the flow of refrigerant into the evaporator based on temperature and pressure. It is a precision metering device — if it sticks open or closed, the evaporator either floods with refrigerant or starves for it, and the A/C stops working correctly. A faulty expansion valve often mimics the symptoms of low refrigerant or a failing compressor, making correct diagnosis critical before replacing expensive components.
At True Truck Parts, we carry OEM-spec expansion valves for major semi truck makes including Freightliner, Kenworth, Peterbilt, Volvo, and Mack. Serving fleets in Mississauga, Brampton, Vaughan, Milton, Oakville, Burlington, and across the GTA. Same-day quoting, Canada-wide delivery.
Symptoms include A/C blowing warm or barely cool air, frost or ice buildup on the evaporator or suction line, the compressor cycling on and off rapidly, or abnormal pressure readings on manifold gauges. A stuck-open valve causes frosting and flooding; a stuck-closed valve causes no cooling at all with very low suction pressure.
Connect a manifold gauge set to the system and compare suction and discharge pressures to the specifications for your refrigerant type and ambient temperature. A stuck-open valve shows low suction pressure and frost on the evaporator. A stuck-closed valve shows very low suction pressure approaching vacuum with high discharge pressure. Confirm by measuring superheat at the evaporator outlet.
Yes, if the compressor failed internally and metal debris entered the system. Debris can lodge in the TXV orifice and prevent it from metering refrigerant properly, which will overheat and damage the new compressor over time. Replace the expansion valve and receiver-dryer along with the compressor when an internal failure is confirmed.
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