Test no. 1                                                                                                                Test no. 2                                                                                                                                                                Test no. 3
            SystemInoperative                                                                                                        Insufficient Cooling                                                                                                                                                      Compressor & Clutch
                                                       High side: Low                    High side: High                   High side: Normal                   High side: High                                 High side: High                   High side: Normal                   Lack of Cooling                 Unusual Noise when            Unusual Noise/Chatter when
                                                       Low side: Low                      Low side: High                   Low side: Normal                   Low side: Normal                                  Low side: Low                 Low side: Normal~High                                                    Clutch Engaged                   Clutch Disengaged
            1. Check system fuse.               No Refrigerant in System          RefrigerantOvercharge              Note:Low side gauge reading        Note:Low side gauge reading                     Restriction                        Thermostatic Switch               Compressor Running                 1. Check all compressor            1. Check electrical system.
            2. Check belt tension.Tighten       Refrigeration is low. May be      1. Connect RobinarRRR              may drop into vacuum while         will be constant & will not                     Liquid line or receiver-drier      (Compressor)                      Rough or Intermittently or           mounting components.             2. Check air gap of clutch.
              or replace belt.                  caused byaleak.                      machine & confirm that          testing.                           drop.                                           shows heavy sweating or            Compressor cuts out too soon.     Inoperative                        2. Check engine components.        3. Check bearing for excessive
            3. Check for current at clutch      1. Connect Robinair RRR              pressures are within            Moisture inSystem                  Air in System                                   frost immediately after point      1.Thermostatic switch             1. Check belt & belt tension.      3. Checked for intermittent          wear.
              coil. If present, check             machine & check for                specification.*                 1. Recover refrigerant from        1. Recover refrigerant from                     of restriction.                      defective or range between      2. Check clutch gap.                 operation or slipping of
              defective clutch coil or            pressure & system leaks.*       2. Correct pressures through         system.*                           system.*                                      1. Remove component clear            points is incorrectly set.      3. Check clutch voltage, amps,       clutch.
              clutch. Ensure good earth         2. Repair any leaks.                 running the appropriate         2. Replace drier.                  2. Replace drier.                                 restriction or renew             2. Replace thermostat.               lead wire &earth.               4. Check drive belt.
              connection.                       3.Vacuum & recharge                  procedures with your            3. Evacuate system &               3. Evacuate system &                              component.                       3. Evacuate system &              4.Turn shaft & make sure that      5.Turn compressor shaft&
            4. Check system controls,             system.*                           Robinair RRRmachine.*             recharge.*                         recharge.*                                    2. Evacuate system &                 recharge.*                         compressor turns smoothly.        make sure it turns
              relay, wiring, thermostat &                                                                                                                                                                 recharge.*                                                         5. Check for low refrigerant         smoothly.
              other control equipment in                                                                                                                                                                                                                                        charge.                         6. Check oil level.
              the system.                                                         Engine Cooling System                                                                                                                                                                      6. Leak test compressor.
            5. Make visual check on all                                           1. Check belt tension &                                                                                                                                                                    7.Test system with RRR
              fittings & for burst or                                                adjust. Use tension gauge.                                                                                                                                                                 machine.*
              leaking hoses.
            6. Check air gap of clutch.                                           2.Test radiator pressure cap &
                                                                                     system thermostat.
                                                                                  3. Check all hoses for                                                                                                                                                                                            *MACSauto recommends using a RobinairRRRmachine to recover,
                                                                                     perishing & leaks.                                                                                                                                                                                             re-gas & carry out diagnostics on mobileair-conditioningsystems.
                                                                                  4. Ensure there is antifreeze in
                                                                                     coolant.
                                                                                  5. Check heater water valve.                                                                                                                                                                                       High Side
                                                                                  Condenser                              ExpansionValve                                                                                                               Expansion Valve
                                                                                  1. May be blocked & not                Test valve with the proper                                                          TMENT                                                                                                                                                    R
                                                                                     having sufficient air flow.           equipment.                                                                        AR                                                                                                                                                       A
                                                                                     Remove bug screen & clean           1. Block valve is probably                                                          OMP             Evaporator                                                                                                 Condenser
                                                                                     condenser.                            stuck closed or blocked.
                                                                                  2. Clearance between radiator            Replace valve & clean                                                                                                                                                               Receiver                                               FRONT OF C
                                                                                                                                                                                                                                                                                                                 Dryer
                                                                                     & condenser must be to                system if necessary.                                                              SSENGER C
                                                                                                                                                                                                             A
                                                                                     system’s designed                                                                                                       P
                                                                                                                         2. If capillary valve responds
                                                                                     dimensions.                           to the test, clean bulb
                                                                                                                           contacts; otherwise replace
                                                                                                                           valve.                                                                                                                    Low Side
                                                                                                                                                                                                                                                                      Compressor
                                                                                                                                                                                                                                                   Automotive Air-Conditioning
                                   AUTO AIR-CONDITIONING                                                                                                                                                                                          An automotive air-conditioner is a system which cools & dehumidifies
                                                                                                                                                                                                                                                      the interior of a car, bus or truck by removing heat & moisture.
                              SYSTEM DIAGNOSISCHART
                                                                                                                                                                                                                                    CHECKTHESE FIVE POINTS
                                                                           (R-134a)                                                                                                                                                 1. Test gauges connected.                                        4. Performance test was conducted.
                                                                                                                                                                                                                                    2. All gauge hoses are purged.                                   5. Gauge readings are documented.
                                                                                                                                                                                                                                    3. System is stabilised (operating temperature).