E.Check Refrigerant System Performance: Engine Off to Start

FIGURE 1 - TESTING HOOKUP:

IMPORTANT: Follow this procedure exactly. It is designed to create enough cooling load to cause the V5 Compressor to go to full stroke which is absolutely necessary for accurate test results. The following test was designed for typical garage conditions - 70-90 degrees Fahrenheit, no sun load. Discharge air temperatures should be at least 20 degrees Fahrenheit cooler than the outside ambient temperature.

1. Connect gage set (Figure 1) to high and low A/C service fittings.

a. Some Cavalier, Corsica and Beretta application's require removal of the in-line pressure switch to read discharge pressure.

b. On some applications the high side fitting is after the orifice tube and reads suction pressure instead of discharge pressure.

2. Check gage set accuracy by reading both gages; readings should be equal. Correct gages as necessary.

3. Set high load test conditions:

a. Start engine and run at idle speed.

b. Open hood, close windows and doors.

c. Set A/C controls to HIGH blower and NORMAL cooling.

d. Run engine for five minutes.

FIGURE 2 - SUCTION VS DISCHARGE PRESSURE:

4. Record and evaluate test results:

a. Record suction and discharge pressures. On systems having condenser fans that cycle on and off, pressure readings should be made when the fan is on.

b. Check diagnostic test chart (Figure 2) and locate intersection of recorded suction and discharge pressures. Determine color of area in which the pressures intersect (white, gray, or black).

c. Go to the proper color heading for Diagnosis and service Procedures. Diagnose in the sequence given to minimize time and expense of repair. Service tips are given with each diagnosis.