Nissan 90 ~93 free download

File name ac system general diagnositic procedures.pdf

A/C SYSTEM GENERAL DIAGNOSTIC PROCEDURES 1993 Nissan Sentra 1993 AIR CONDITIONING & HEAT A/C General Diagnostic Procedures Diagnosis is an important first step in A/C system servicing. To save time and effort, systems should be carefully checked to identify the causes of poor performance. By using the following diagnostic charts, defective components or system problems can be quickly located. To identify problems that are specific to one system, refer to the repair section of this manual. The charts in this section apply to all systems. PREPARATION FOR TESTING 1) 2) 3) 4) 5) Attach Low and High pressure gauges. Start engine and allow to warm up. Set system to COOL and blower to HIGH. Open car doors and hood. Run engine at fast idle for 2-3 minutes. AIR CONDITIONING SYSTEM PERFORMANCE CHECK AIR CONDITIONING SYSTEM PERFORMANCE CHECK TABLE PERFORM TESTS: Temperature Check 35-45 PERFORM TESTS: Visual Check * Compressor * Condenser * Receiver-Drier * Sight Glass * High Side Lines ЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎ ЎЎЎЎЎЎЎЎ ЎЎ ЎЎЎЎ Ў SHOULD BE: ЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎ ЎЎЎЎЎЎЎЎ ЎЎ ЎЎЎЎ Ў Quiet with no leaks Free of obstructions Dry and warm to touch Clear or few bubbles Dry and warm to touch ў * Switch to LOW blower. * Close doors. * Check outlet temperature. ЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎ ЎЎЎЎЎЎЎЎ ЎЎ ЎЎЎЎ Ў SHOULD BE: IF: ЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎЎ ЎЎЎЎЎЎЎЎ ЎЎ ЎЎЎЎ Ў F Temperature Check Is: Too warm - Check control lever operation, heater water valve, cooling system and gauge readings. IF: Visual Check Shows: Noisy - Check belts, oil level, seals, gaskets, reed valves. Blocked - Clean off. Plugged - Flush or replace. Frosty - Check for restriction, replace desiccant. Bubbly, foamy or streaks - Check gauge readings. Frosty or very hot - Check for restriction or overcharge. * Low Side Lines Dry and cool to touch Frosty or warm - Check for restriction, low charge or bad valve. Frosty - Check for moisture or restriction. Check sensing bulb. Frosty or warm - Check gauge readings for valve malfunction. Freezing or warm - Check expansion valve, STV or thermoswitch. IF: * Expansion Valve Dry * STV Dry and cool to touch * Evaporator Dry and cold to touch PERFORM TESTS: Gauge Readings * High Side Gauge * Low Side Gauge Fig. 1: