Insufficient Cooling

DIAGNOSTIC PROCEDURES FOR VARIABLE DISPLACEMENT ORIFICE TUBE (VDOT) SYSTEMS

The procedures in the following charts will help you diagnose V5 compressor and VDOT refrigerant system problems causing insufficient cooling. They must be used in conjunction with other appropriate service information.


The V5 compressor is a variable displacement compressor which matches air conditioning demand by changing its stroke, instead of cycling its clutch. A control valve located in the rear head of the compressor senses compressor low side pressure and causes the compressor mechanism to change stroke. Because the V5 compressor always runs and the system does not cycle, these diagnostic procedures differ from those used for fixed displacement systems. By using these procedures, you will avoid needlessly replacing A/C components.


STEP 1-Preliminary Checks


Repair the following as necessary. If discharge air temperature with A/C on is normal after making the following repairs, the system is operating properly.


- A/C fuse

- A/C blower operation.

- Clutch coil and rear head switch(es) connections.

- Compressor belt. Adjust or replace if damaged or missing.

- Engine cooling fan operation.

- Condenser - Check for restricted air flow.






VDOT AIR CONDITIONING SYSTEM DIAGNOSIS CHARTS

If the Preliminary Checks does not return the system back to normal operation refer to the accompanying figures for diagnosis of the VDOT air conditioning system.





STEP 2 Chart: Checking Refrigerant Charge.





STEP 3 Chart: Checking Compressor Clutch Engagement.








STEP 4 Charts: Checking System Performance.





STEP 5 Chart: Gray area Diagnosis and Service.





STEP 6 Chart: Striped area Diagnosis and Service.





Step 7 Chart: Control Valve Diagnosis.