Pressure Temperature Relationship.

Pressure Temperature Relationship.

Note: Pressures shown are under exact conditions (see test conditions) and are not necessary true for every car checked. Ambient Temperature is given as the air surrounding the condenser and is taken 5 cm in front of the condenser.

Test Conditions.

Use a large fan to substitute for normal ram air through the condenser. Engine adjusted to fast idle speed.

All conditions equivalent to 30 m.p.h. or 48 km/h.

Normal operating ambient temperature range is: -24 to 43°C.

Normal operating evaporator temperature range is: -12 to 0°C.

Under normal running conditions system pressure should be, as follows:

Low side: 1.05 to 2.10 kgf/cm2 1.034 to 2.06 bar 15 to 30 lb/in2

High side: 13.00 to 14.40 kgf/cm2 12.75 to 14.34 bar 185 to 205 lb/in2

Manifold Gauge Set Check Procedures

Refrigerant Slightly Low.

Complaint.

Little or no cooling.

Condition.

1. The low side gauge reading is too low.
2. The high side gauge reading is too low.
3. A stream of bubbles evident in the sight glass.
4. The discharge air from the evaporator only slightly cool.

Diagnosis.

The system low on refrigerant due to slight leak.

Correction.

1. Test the system for leaks.
2. Depressurise the system.
3. Repair the leaks, and if necessary renew hoses or units.
4. Check the compressor oil level. The system may have lost oil due to leakage.
5. Evacuate the system using a vacuum pump.
6. Recharge the system with new refrigerant.
7. Operate the system and check the performance.