"**What this part does**
Allows refrigerant to flow in one direction only, stopping high-pressure gas from flowing back into the compressor or into the low side when the compressor stops.
**Where it is installed**
The Compressor Check Valve (One-Way Valve) is located in the compressor port or cylinder-head passage on the suction or discharge side.
**Symptoms of a failed check valve**
A worn or damaged check valve shows up as one or more of these symptoms:
- Poor cooling — the system cannot hold its pressure
- Pressure equalises very quickly after shutdown, so the compressor restarts against a high load (hard start, belt chirp)
- Refrigerant back-flow causing a knock or slugging on start-up
- Valve stuck closed — no flow, with very high pressure on one side
- Debris, swollen seal or a broken spring found when the valve is removed
**When to replace**
Replace the valve whenever it is contaminated or stuck, and every time the system is opened after a compressor failure (flush the system too).
**Why choose this part**
Supplied as a direct replacement for the original part. Always compare the dimensions, hole layout and finish with your original part before ordering.
**Ordering note**
Check valve direction, thread and size against the original part before ordering — a reversed valve will not flow.
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