System Diagnosis - VDOT

VDOT A/C System Diagnosis (Part 1 Of 5):

VDOT A/C System Diagnosis (Part 2 Of 5):

Use the following diagnostic tables in order to diagnose insufficient cooling conditions with the following Systems:
^ The V5 compressor
^ The VDOT refrigerant system

Use these procedures in conjunction with other appropriate service information.

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

Preliminary Checks
Repair the following components as needed. If the air discharge air temperature with the A/C ON is normal after repairing the following components, the system is operating properly:
^ The A/C fuse
^ The A/C blower operation
^ The temperature door

Move the temperature door rapidly from the COLD position to the HOT position. Listen for the temperature door hitting at each end. Adjust the door as needed. (Cable-operated temperature door only)
^ The clutch coil
^ The rear head switch connections
^ The drive belt

Adjust the belt as needed. Replace the belt if the belt is damaged or missing.
^ The engine cooling fan operation
^ The condenser

Inspect the condenser for restricted air flow. Consult Dealer Technical Bulletins and the Service Guild for updates on the A/C system.

Checking System Performance:

VDOT A/C System Diagnosis (Part 3 Of 5):

VDOT A/C System Diagnosis (Part 4 Of 5):

Checking System Performance

IMPORTANT: This test is designed for the following garage conditions:
^ 21°-32°C (70°-90°F)
^ No sun load

Normal discharge temperature is typically at least 7°C (20°F) cooler than the ambient temperature. Follow the steps in this test exactly. The test is designed in order to create enough cooling load in order to cause the V5 to operate at full stroke. This condition is absolutely necessary in order to obtain accurate test results.

VDOT A/C System Diagnosis (Part 5 Of 5):

Control Valve Diagnosis

IMPORTANT: Follow the steps in this test procedure exactly. This test is designed in order to create a low cooling load. This condition causes the V5 compressor to operate at less than full stroke. This condition is absolutely necessary in order to obtain accurate test results.