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Insufficient Or No A/C Cooling

INSUFFICIENT OR NO A/C COOLING

Test Step Result Action To Take
A1 - VERIFY CONDITION
* Verify Condition System Cooling Properly Instruct Driver On How To Use System.
" System Not Cooling Properly Go To A2
A2 - CHECK A/C CLUTCH
* Does A/C Compressor Clutch Engage? Yes Go To A3
" No See Compressor Clutch Circuit Diagnosis
A3 - CHECK UNDER HOOD
Under Hood Check For:
  • Loose, Missing Or Damaged Compressor Drive Belt.
  • Loose Or Disconnected A/C Clutch Cycling Pressure Switch Wires Or Connectors.
  • Disconnected Resistor Assembly.
  • Loose Vacuum Lines Or Misadjusted Control Cables.
In-Car Check For:
  • Blown Fuse/Proper Blower Motor Operation.
  • Vacuum Motors/Temperature Door Movement - Full Travel.
  • Control Electrical And Vacuum Connectors.
 Components Check Okay, But Still Not Cooling Properly. Go To A5
" Components Do Not Check Okay Or Improperly Adjusted. Repair And Go To A4
A4 - CHECK SYSTEM OPERATION
* Check System Operation System Cooling Okay Condition Corrected Go To A1
" System Not Cooling Okay Go To A5
A5 - CHECK PRESSURE CLUTCH CYCLE RATE
* Use Refrigerant Pressure/Clutch Cycle Rate And Timing Evaluation Charts.
  1. 1. Attachment Manifold Gauge Set.
  2. 2. Set Function Lever At: MAX A/C.
  3. 3. Set Blower Switch On HIGH.
  4. 4. Set Temp Lever Full Cold.
  5. 5. Close Doors And Windows.
  6. 6. Using thermometer, Check Temperature At Center Discharge Register. Record Outside Temperature.
  7. 7. Run At Approximately 1500 RPM W/Compressor Clutch Engaged.
  8. 8. Stabilize With Above Conditions For 10-15 Minutes.

* Check Compressor Clutch OFF/ON; Time With Watch. See charts for normal clutch cycle and timing rates.		 Compressor Cycles Very Rapidly Go To A5
" Compressor Runs Continuously (Normal Operation In Ambient Temperature Above 26.6°C (80°F) Depending On Humidity Conditions). Go To A7
" Compressor Cycles Slow Go To A6
A6 - CHECK EVAPORATOR TUBES TEMPERATURE
  • Bypass Clutch Cycling Pressure Switch With Jumper Wire. Compressure on Continuously.
  • Hand Feel Evaporator Inlet And Tubes.
 Outlet Tube Same Temperature (Approximately -2.2°C To -4.4°C or (28°F To 40°F) or Slightly Colder Than Inlet Tube (After Fixed Orifice). REPLACE Expansion Valve. Go To A7
" Inlet Tube Warm Or (After Fixed Orifice) Colder Than Outlet Tube. Go To A8
A7 - CHECK PRESSURES
Check System Pressures. * Compare Readings With Normal System Pressure Ranges Clutch Cycles Within Limits. System OK, Go To A1
" Compressor Runs Continuously (Normal Operation In Ambient Temperature Above 26.6°C (80°F) Depending On Humidity Conditions). Go To A9
" Compressor Cycles High Or Low: ON Above 358 kPa (52 psi) OFF Below 144 kPa (21 psi) REPLACE Expansion Valve.
" " System Okay, Go To A1.
" " System Not Okay, Go To A8.
A8 - CHECK FOR LEAKS
Leak System Check Leak Found Repair, Discharge, Evacuate And Charge System. System Okay, Go To A1.
" No Leak Found Low Refrigerant Charge Or Moisture In System. Discharge, Evacuate And Charge System. System Okay.
A9 - CHECK CLUTCH CYCLING OFF
Disconnect Blower Motor Wire And Check For Clutch Cycling Off At 144 kPa (21 psi) (Suction Pressure). Clutch Cycles Off At 144 kPa (21 psi) RECONNECT Blower Motor Wire. System Okay, Go To A1.
" Pressure Falls Below 144 kPa (21 psi) REPLACE Expansion valve. System Okay, Go To A1.
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