{"model":"mk3","model_name":"MK3 Supra","vehicle":"Toyota Supra A70 (1986.5–1992, 7M-GE / 7M-GTE)","document":"Repair Manual","section":"AC","section_name":"Air Conditioning System","page":18,"pages_in_section":46,"title":"Checking of Refrigeration System with Manifold Gauge (Cont'd)","section_header":"Air Conditioning System — Troubleshooting","ocr_text":"AC-18\nAIR CONDITIONING SYSTEM — Troubleshooting\n\nChecking of Refrigeration System with Manifold Gauge (Cont'd)\n\nNo. | Symptom seen in refrigeration system | Probable cause | Diagnosis | Remedy\n\n1 | During operation, pressure at low pressure side sometimes becomes a vacuum and sometimes normal | Moisture entered in refrigeration system freezes at expansion valve orifice and temporarily stops cycle, but normal state is restored after a time when the ice melts | Drier in oversaturated state\n↓\nMoisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant | (1) Replace receiver and drier\n(2) Remove moisture in cycle through repeated vacuum purging\n(3) Charge refrigerant to proper amount\n\n2 | Pressure low at both low and high pressure sides\n\nBubbles seen in sight glass\nInsufficient cooling performance | Gas leakage at some place in refrigeration system | Insufficient refrigerant in system\n↓\nRefrigerant leaking | (1) Check with leak detector and repair\n\n(2) Charge refrigerant to proper amount\n\n3 | Pressure low at both low and high pressure sides\n\nFrost on tubes from receiver to unit | Refrigerant flow obstructed by dirt in receiver | Receiver clogged | Replace receiver\n\n4 | Pressure too high at both low and high pressure sides | Unable to develop sufficient performance due to excessive refrigerant in system\n\nCondenser cooling insufficient | Excess refrigerant in cycle → refrigerant overcharged\n↓\nCondenser cooling insufficient → condenser fins clogged or fan motor faulty | (1) Clean condenser\n(2) Check fan motor operation\n(3) If (1) and (2) are normal, check refrigerant amount\nHINT: Vent out refrigerant through gauge manifold low pressure side by gradually opening valve.\n\n5 | Pressure too high at both low and high pressure sides\n\nFrost or large amount of dew on piping at low pressure side | Trouble in expansion valve or heat sensing tube not installed correctly\n\nRefrigerant flow cut off | Excessive refrigerant in low pressure piping\n↓\nExpansion valve opened too wide | (1) Check heat sensing tube installation condition\n\n(2) If (1) is normal, test expansion valve in unit\n(3) Replace if defective\n\n6 | Pressure too high at both low and high pressure sides | Air entered refrigeration system | Air present in refrigeration system\n↓\nInsufficient vacuum purging | (1) Replace receiver and drier\n(2) Check compressor oil to see if dirty or insufficient\n(3) Vacuum purge and charge new refrigerant\n\n*Note at No. 6\nThese gauge indications are shown when the refrigeration system has been opened and the refrigerant charged without vacuum 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transcript of a scanned Toyota factory manual page; verify critical values (torque specs, part numbers) against the image."}