H: Insufficient or No A/C Cooling

H1 CHECK A/C SYSTEM PRESSURES

- Check system operation. Verify the refrigerant pressure is greater than 344.75 kPa (50 psi).

- Does system cool properly?

- Yes
Instruct vehicle owner on proper use of the system.

- No
Go to H2.

H2 CHECK A/C CLUTCH

- Check A/C clutch operation.

- Does the A/C clutch engage?

- Yes
Go to H3.

- No
Refer to A/C compressor clutch circuit diagnosis.

H3 COMPONENT CHECK

- Underhood check of the following:

- Loose, missing or damaged A/C compressor drive belt.

- Loose or disconnected A/C clutch or A/C cyclic switch wires/connectors.

- A/C clutch assembly damaged.

- Inside vehicle check for:

- Blown fuse/proper heater blower motor operation.

- Vacuum control motors and A/C air temperature control door movement - full travel.

- Control electrical and vacuum connections.

- Are components OK?

- Yes
Go to H5.

- No
Service and Go to H4.

H4 CHECK A/C SYSTEM OPERATION

- Check system operation.

- Does system operate properly?

- Yes
Condition corrected. Go to H1.

- No
Go to H5.

H5 CHECK A/C CLUTCH CYCLING RATE

- After preparing vehicle as follows:

- Hook up manifold gauge set.

- Set function selector lever at MAX A/C. Set heater blower motor switch on HI.

- Set temperature lever full COOL. Close doors and windows.

- Use a thermometer to check temperature at center discharge A/C register, record outside temperature.

- Run engine at approximately 1500 rpm with A/C clutch engaged.

- Stabilize with above conditions for 10-15 minutes.

Normal A/C Cycling Pressure Switch Rates And Times - Evaporator Core Orifice Type System:

- Check A/C clutch off/on time with watch. Refer to the chart for normal A/C clutch cycle timing rates.

- Does the A/C clutch cycle very rapidly (5 seconds on, 5 seconds off)?

- Yes
Go to H9.

- No
Go to H6.

H6 CHECK A/C CLUTCH OPERATION

- Verify A/C clutch operation.

- Does the A/C clutch run continuously?

- Yes
Go to H7.

- No
Retest. Go to H5.

H7 CHECK SYSTEM PRESSURES WITH A/C CLUTCH CYCLING RATES

- Compare readings with normal system pressure ranges.

- Does the A/C clutch cycle within limits?

- Yes
If the system pressure is within limits, the system is OK. Go to H1. If the system pressure is not within limits, SERVICE as required.

- No
Go to H8.

H8 CHECK A/C CLUTCH HIGH OR LOW CYCLING RATES

- Compare readings with normal system pressure ranges.

- Does the A/C clutch cycle high or low ON above 359 kPa (52 psi) OFF below 138 kPa (20 psi)?

- Yes
Replace A/C cyclic switch. DO NOT discharge system. A/C cyclic switch fitting has Schrader valve. Check system. If OK, GO to H1. If not OK, reinstall original A/C cyclic switch.

- No
Go to H5.

H9 CHECK SYSTEM FOR REFRIGERANT LEAK

- Leak check system.

- Is system leaking?

- Yes
Service test discharge, evacuate and charge system. System OK, Go to H1.

- No
Low refrigerant charge or moisture in system. Discharge, evacuate and charge system. Go to H4.