Articles/Aircon Parts and Common Problems

Expansion valve (EEV/TXV) fault signs

The expansion valve controls refrigerant flow. When that control becomes unstable, cooling can swing between too weak and too aggressive. Because those symptoms can overlap with sensor, board, or refrigerant-path issues, valve replacement should come after a clear check sequence.

Quick verdict

Most likely when

Cooling swings between normal and weak without setting changes
Performance drops under higher load, then partially returns
Pattern repeats after short-term relief work

Often not this

Sensor drift affecting control decisions
Control-board command issues
Refrigerant-path issues unrelated to valve control

Check first

Model-specific valve location and type (EEV or TXV)
Sensor input quality and connector stability
Pressure and temperature behavior across a full run cycle

Primary question

If someone says my expansion valve is faulty, what should I check first before agreeing to replacement?

Where this part sits and what it does

Valve location depends on system design. Some are placed near the outdoor assembly, others near the indoor coil path.

Its job is to meter refrigerant flow so cooling stays stable. If flow control drifts, comfort can become inconsistent.

Symptoms this part can cause

Valve-related problems usually appear as unstable cooling patterns, not always total failure.

Cooling strength changes during the same run cycle
System performs worse under heat load, then partially recovers
Room comfort varies even with the same thermostat setting
Issue returns after temporary fixes

Common look-alikes before you blame the expansion valve

Several issues can look like valve trouble.

Indoor or outdoor sensor drift
Control-board command instability
Refrigerant leak or restriction elsewhere in the circuit

What to check before replacing the expansion valve

Start with checks that separate valve behavior from control and sensing issues.

Confirm valve location and type for your exact system
Confirm sensor readings are believable against real operating temperature
Check pressure and temperature trend across startup, steady run, and load change

What to ask your technician to show

Ask for part-specific evidence, not only a broad cooling complaint.

What test result points to valve control, not just weak cooling
What was ruled out first (sensor, board, refrigerant leak path)
Why replacement is the next step now, not later

When to get urgent help

Get urgent help if cooling swings are severe and repeated, especially after recent repair attempts.

Repeated instability can push larger failures if left unresolved.

When replacement makes sense and when it does not

Replacement usually makes sense when valve-control behavior stays abnormal after sensor and board paths are checked.

It usually does not make sense when the recommendation is based on symptoms alone without trend evidence.

Need help with your own unit?

Tell us what is happening. We will assess first, advise one clear next step, and you decide.

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