Thermo King – Testing the Condenser Check Valve

1. Front seat the condenser pressure bypass check valve.
2. Operate the unit in high speed cool and cover the condenser coil to build discharge pressure:
• R-12, R-401B and R-134a = 250 to 250 psig
• R-502, R-22, R-402A, R-403B and R-404A = 300 to 350 psig
3. Pump down the low side, while keeping the condenser coil covered.
4. When discharge pressure begins to decrease and the low pressure gauge reaches a 10 inch vacuum, remove the condenser cover to reduce discharge pressure approximately 100 psig. STOP THE UNIT.
5. Observe the manifold high pressure gauge:
• a pressure increase – indicates the condenser check valve leaks.
• receiver tank pressure must remain above condenser pressure – indicating a good condenser check valve.

NOTE: Receiver tank pressure may decrease slowly but must remain higher than the gauge manifold’s high pressure.

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