FATC 49 e) PRESSURE TEST USING MANIFOLD GAUGES This is a method where trouble is detected and repaired by using manifold gauge. The manifold gauge indicates the refrigeration cycle high and low pressure side pressures on the respective gauge. NOTE Make sure following conditions are fulfilled before getting the correct gauge readings (after engine has warmed –up) Engine speed 1500rpm A/C inlet temperature (Ambient Temperature) 30° - 35° C (86° - 95° F) Blower speed High Temperature Control Full cold Reference value before AC operation at both high and low pressure sides 5-8 kg/ cm2 (0.5 - 0.8 MPa) Based on the values the following conclusions can be inferred and further troubleshooting can be done. Low Pressure side in kg/cm2 ( M Pa) High Pressure side in kg/cm2 ( M Pa) Remarks Symptoms Possible reasons 1.5-2.5 (0.15-0.25) 14-16 (1.37-1.57) System pressure is normal Normal cooling AC system working normal 0.5-1.0 (0.05-0.1) 7-10 (0.69-0.98) Pressure low Insufficient cooling 1. Refrigerant quantity too small. 2. Gas leakage. Vacuum 5-6 (0.5-0.6) Refrigerant fails to circulate No cooling experienced Clogging of AC cycle. Initially 1.5-2.5 (0.15 -0.25) and later vacuum Initially 14-16 (1.371.57)and later 7-10 (0.69-0.98) Moisture present in system. Initially works normally but later no cooing experienced Freezing of expansion valve due to presence of moisture. 4-6 (0.4-0.6) 7-10 (0.69-0.98) Pressure on low pressure side is high and pressure on high pressure side is low. No cooling. Compressor Defective.
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