System Diagnosis - VDOT

Steps 1-11:

Steps 12-20:

Steps 21-35:

Steps 36-46:

The following chart will help you to diagnose V7 compressor and VDOT refrigerant system problems that cause insufficient cooling. Use the chart in conjunction with other appropriate service manual information.

The V7 compressor is a variable displacement compressor. The compressor matches air conditioning demand by changing stroke instead of cycling the clutch. A control valve that is located in the rear head of the compressor senses compressor low side pressure. The valve then causes the compressor mechanism to change stroke. These diagnostic procedures differ from those used for fixed displacement systems because the V7 compressor always runs and the system does not cycle. Use these procedures in order to avoid needlessly replacing A/C components.

If the discharge air temperature with the A/C is normal after you make the following repairs, then the system operates properly. Repair the following components as necessary.
^ The fuse
^ The blower motor operation
Refer to Blower Motor and Fan Replacement (RPO C42) or Blower Motor and Fan Replacement (RPO C60 and C68).
^ The clutch coil and the rear head switch(es) connections
^ The compressor belt
Adjust or replace the belt if the belt is damaged or missing.
^ Engine cooling fan clutch operation Refer to Fan Clutch Replacement in Cooling System.
^ Inspect the condenser for restricted air flow.

For a description of the RPO Code(s) shown in this article/image, refer to the RPO Code List found at Vehicle/Application ID.

Application and ID